Featured: A cheap dyno/skid-pad program for iPhone and iPod Touch, some great podcasts for your PC and/or mp3 player and an accessory from one of our sponsors.
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The reason for this post — I’ve just purchased my first actual iPod. I was a long-time satisfied user of an iRiver Clix that was either lost or stolen on a trip to New Jersey last summer. Faced with the decision, I decided to buy a factory refurbished 4GB iPod Nano 3rd Generation from the Apple store online. With shipping it was around $85 — a great price if you ask me. I grudgingly admit that this little gadget is a huge upgrade. I still have a fundamental issue with the proprietary Apple compression format, but I must admit that it sounds great and having video in your player is also a huge plus.

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This has my wheels turning in that direction, so here are a few Saab-related revelations that accompanied the iPod-ing of my life. (For a non-Saab related revelation, see here.)
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I’ll start with the great-looking iPod/mp3 add-on kit for your 9-3 available from Elkparts. This setup avoids the compromised sound associated with FM transmitters and other add-on adapters. Using a direct interface, this harness gets you connected the right way. Works for me, except that I don’t own a 9-3!

(Swade has looked at this option in the past, but I’m assuming that since the Viggen is no more that little project went by the way.)
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I love this little software package from Dynolicious for Apple iPhone or Apple iPod Touch. It uses the accelerometer inside the device to measure acceleration in all directions that can be used to translate engine output, 0-60 times, quarter mile time, lateral grip and braking performance. For only US$13, you get a little performance monitor for any car! I’m sure that it’s not very precise, but for $13 I could live with that. It requires no connections to the car and you can download the results to your PC. Very cool.

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If you haven’t checked out the Saabcast site on Saabusa.com, have a look. There are a few great video podcasts there. I found a couple of additional videos from Saab USA on iTunes that I could download free of charge, including this video on “How to change a tire.” Nicely done, and the Dame Edna 9-5 and an attractive actress make it easy on the eyes, for sure.

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GM Europe has a cache of iPod-ready videos for we Saabisti, too. Some very polished stuff such as this video of the Saab 9-X Air concept with Mark Adams.

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Finally, there are a few Canadians out there actually racing Saabs! Swade has featured JL Racing before, but they’ve posted some great information on their website including a few great audio podcasts (click on the podcasts banner on the right column of the front page). They certainly had some late-season success in the Canadian Touring Car series with three wins in late August! I highly recommend all three podcasts for some great Saab techie tidbits.

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Fellow Tassie Saabnut, Drew B, is at it again. He’s always looking for a project and many of them involve cars that other people would just pass by. Take this Saab 900 S, for example. It was a low mileage car owned by an old lady – a classic vehicular pickup – but it had also had its roof caved in courtesy of a wayward tree that got lost during a wind storm. Perfect.

I no longer have the Here are the ‘before’ photos…..

……and here’s what Drew got up to last weekend:

Drew picked up the car for a song with the intention of fixing it up for his mother to drive. It’s only done around 90,000kms and apart from the dented lid, it’s squeaky clean.

Getting the replacement roof panel was a story in itself. Drew ordered the panel and it turned up in it’s box, though when he checked it out he found that it was a 9-5 roof panel, not a 900 panel. A check of the database showed that the 900 roof panel was now obsolete and there were none in stock. A few phone calls, discussions and arguments later, it was found that the panel was, in fact, still available, despite the database showing it as being unavailable. The 9-5 panel was shipped off and the new one arrived a few weeks ago.

Back to the repairs…..

So how do you remove a roof panel? Well, it helps if you have one of these to drill out all of the spot welds.

So the roof is now off. I’m sure we’ll get some updated pics when the new roof is attached and the car is put back together. Then Drew can get on to fixing the silver convertible, restoring the blue 99……..

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Seeing I have no technical expertise, I thought I’d post the question here and let you lot get in on the act. Renee’s question is a two-parter, as follows:

I love my used Saab 9-3t convertible 2004, which I bought about six months ago. I wondered if you could help me with a techie question?

Ever since I bought the car it has had a problem with randomly revviing up as I am driving. Do you have any idea what could be causing this and how I can get it fixed if it is random?

Secondly, what brand gas is best? I was using Chevron premium but have switched to their regular due to cost. However, I hate to support mid east gas when I could buy American…any suggestions?

Firstly, congratulations on your wise choice in picking up an irrestivertible. A fine drive in anyone’s terms. I suggest getting a BSR upgrade for some enhanced zippiness. It’ll really bring it to life. Our email circle here in Australia have been discussing the BSR unit over the last few days and one guy who’s done the modification to his 1.8t SportCombi absolutely loves it.

Of course, that’s got nothing to do with your questions, but I thought I’d offer it up anyway.

On the first issue, I’ll have to defer to those that tune in here and actually know what they’re on about. Something electrical, perhaps?

On the second issue, I have to confess that I’m an absolute believer in the marketing of the oil companies. I only use premium. BP Ultimate, actually. I don’t know if it’s just phychological, but my cars definitely do feel like they’re running better, and are more responsive, on the premium juice.

Standard fuel here in Australia is 91 Octane, though I think we use a slightly different measuring system to the US. The BP Ultimate stuff is 98 octane, so it’s certainly supposed to have some more zip than the normal stuff.

I think it’s even more important to use the good stuff if your car is modified and the new tuning is based on an expectation for good fuel.

In terms of the origin of the oil – stuff it. Everyone you’re buying it from is way wealthier than you, so you’re lining someone’s pockets either way. Just whose pockets they are is almost impossible to tell at any given filling station. The only way you could be sure is to buy a diesel and start making your own.

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They’re just my token thoughts. Over to the rest of you.

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This is a useful addition for those who arrive at SaabUSA’s website and don’t have much background with what are going to be Saab’s two core technologies for the next few years (along with hybrid technology when it comes).

Turbocharging isn’t new, of course, but there will still be some who find the graphics and the brief lessons useful in understanding how it works (and why their Saab moves so effortlessly up hills!).

XWD is new, so I’m sure some people are going to find that very useful as the word spreads around.

We’ve been calling on Saab to talk more about their capabilities and sell their credentials a bit more, so this is a definite step in the right direction.

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Thanks to Dan S from Racing Ready for passing this on.

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The question comes from Dan, who writes:

I purchased a Turbo X back in May, I have noticed that during the first minute or three of a cold start it has superior performance and a deeper exhaust note (perhaps more air intake?, wish it would stay that way). I have consulted many mechanics and received no positive answer. Perhaps, with your expertise you could lend some information on this matter. Thank you. Sincerely, Dan

Seeing as how I don’t actually have a clue about these things (I am a mechanical gimp – but learning), I passed the query on to our friendly GM Master Technician, Tedjs, who provided the following:

He is basically experiencing two things – one is advanced ignition timing that is used during the engine warmup cycle which essentially is used to pre-heat and ignitie the richer air fuel mixture in the cylinder. This will produce some additional mid-range torque and power during warmup.

The other thing is that exhaust cam-phasing is commanded to add some additional valve overlap on engine warm-up to light off the catalytic convertor. Basically what they are doing is in conjunction with the turbo is letting some additional air run through the cylinder to help heat up the exhaust quicker. That is causing the change in the exhaust note in conjunction with timing. I have noticed it on my car as well.

The 2.8L warms up amazingly quick – more so than any car I have ever owned. Even in cold outdoor temps it really gets up to operating temperature in short order to maximize fuel economy. Compared to the lump of cast iron that was in my old car which took a lifetime to warm up – and used a lot of fuel in the process.

So if you’re experiencing the same symptoms as Dan when you start your V6 in the morning, now you know why. Enjoy those first few minutes. If you’ve got a cocky neighbor with an A4 3.2 quattro, perhaps right on startup is the time to show ‘em who’s boss

My thanks to Tedjs for once again stepping up to the plate.

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We’ve had several discussions about oils and this Q&A seems to be pretty comprehensive and useful. I thought it would be a good resource to record here for future reference.

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We get asked many oil related questions every day and decided to put some of the most frequently asked ones to an Oil Expert called John Rowland. He has been the Chief R&D Chemist for Fuchs/Silkolene for many years and previously developed ahead of their time ester based oils for the RR Jet industry. What he doesn’t know about oil is not worth knowing in our opinion!

1) How is an oil manufactured; transformed from the black sludge that comes out of the ground, into the nectar-like substance we pour into our cars and bikes?

Crude oil, which is usually very thin, (contrary to popular belief!) is distilled into light and heavy fractions, with several intermediate ones. (The evil left-overs are used to fuel the 15 million cc/40RPM diesels in the giant oil tankers that bring the crude to the refinery.)

The lighter fractions, usually more than 90% of the original crude, are converted into petrol and diesel. Some of the heavier oils, (still dark and smelly!) go through several processes to clean them up and remove wax. Out of about a dozen oily products 4 clear, bright amber oils are commonly used to blend modern engine and gear oils. These are roughly equivalent to SAE 10, 20, and 30 engine rating and 140 gear rating. Oil refineries also produce all sorts of gases and chemical compounds which can be used to build up ‘tailor made’ lubricants: synthetics!

2) What are the most important substances added to the refined base oils? What do they do?

In the Dark Ages, engines used blends of refined mineral oils ‘straight’, with nothing added. The trouble was, even in the slow-revving engines of 80 years ago the oil didn’t last very long, and the engines didn’t either.

Black sludge and corrosion were the killers, and both were tackled in the 1950s with detergent and antioxidant chemicals. (When I was a lad, I used to visit a mate of my Dad’s who rebuilt the very popular side-valve Ford engines. The thick crap inside these things was unbelievable! The valve tappets were moving in holes in solid blocks of carbon!) The detergents washed the carbon from fuel combustion off the bores and out of the ring grooves, and at the same time reduced bore and piston ring corrosion.

The antioxidants stopped the oil reacting with oxygen in the air, which cut acid sludge formation which in turn reduced corrosion and oilway blockages. Some antioxidants had the useful side-effect of reducing wear as well. This added up to longer oil and engine life, both improving about three times. (Straight oil had to be changed every 1000miles, and even lightly-stressed engines running on it were ready for a full overhaul at 15-20,000.) OK, I admit there were design and metallurgical improvements, but they needed that vital ‘liquid component’ to be fully effective.
Later came dispersant compounds which held the carbon as tiny particles in the oil which didn’t settle out anywhere, and slipped through the oil filter as if it wasn’t there.(Solid bits in well-used modern oil are about 1/1000mm across; the pores in an oil filter are at least 15 times bigger.)
The other big problem with oil used to be cold starting. It was usual to have SAE 20 Winter or ‘W’ grades, and SAE 30 or 40 Summer grades, and even the so-called Winter types would defeat the starter in serious cold weather. Unfortunately, oil is very thick when it’s cold, and very thin when it’s hot. To have an oil thick enough to look after a
hard working engine, you had to use a grade which was too thick when it was cold.

The answer was (and is) multigrade! What was needed was an oil that behaved like a 20 ‘W’ grade in the cold, but only thinned down to a SAE 40 or 50 when really hot; yes, 20W/50! This can be done by mixing thin oil with thick polymers based on plastics and synthetic rubbers; these don’t do much in the cold, but as the oil warms up they unwind and thicken it up to some extent. The oil still thins down, but not as quickly as a polymer-free or monograde type.

Multigrades started to catch on around 1960, but these pioneer types were easily ruined by mechanical shear effects, more so in gearboxes than engines. These days the better quality polymers resist shear even in combined engine/transmissions, so it is essential to use good quality shear-resistant types in a gearbox fed by the engine (such as the traditional mini!), which gives its oil a hard time in both engine and gearbox.

Incidentally, there are large amounts of these additives and polymers in there, it’s not just ‘a little bit of this, a little bit of that’! A good quality mineral 10W/40 can be 80% base 20% additive chemistry, and guess which is the expensive ingredient!

3) What are the differences, in layman’s terms, between mineral, semi-synthetic and fully-synthetic engine oil? (In terms of structure and performance.)

Before we get into details, the first thing to realise that there is no chalk and cheese difference between mineral and synthetic based oils. After all, the chemical compounds which make mineral engine oils so much better are themselves synthetic.
Synthetic lubricant bases are stepwise improvements on mineral oil, with more desirable properties and fewer undesirable ones. The second important point is that there’s no one thing called ‘synthetic’! There are several different types of synthetic lubricant, and to say something like: ‘the Supergrunt GTI TURBO must have a full synthetic’ is meaningless unless the ‘expert’ explains what sort of synthetic he means.

Equally, to imply that dreadful things will happen if the 1970 RV8 is run on anything other than good’ ole mineral oil is ridiculous. It may not need a 2007 synthetic, but it isn’t going to come to any harm if the owner uses a 2007 synthetic!

The most basic type of synthetic is really a special mineral oil. Known as ‘hydrocracked’ bases, these are made in oil refineries by putting certain types of mineral fraction through special processing, so they cost more than the usual mineral types but not much more. They are useful because they resist evaporation at high temperatures. Although used for years for genuine technical reasons, they are now popular with marketing men because the magic sexy word ‘synthetic’ can legitimately be printed on the label without spending much on the oil inside the can!

Yes, all low-cost ‘synthetics’ contain anything from a few percent to 20 percent (i.e. ‘semi-synthetic’) of special mineral oil. Using fairly simple chemical compounds or gases from oil refineries or other sources, it is possible to ‘synthesise’ or build up tailor-made lubricant molecules which have very desirable characteristics, such as great resistance to cold, heat, evaporation losses or excessive thinning as they get hot. These are the true synthetics, and the two that are used in engine oils are PAOs (poly alpha olefins) and esters.

Neither is cheap! PAOs are related to mineral oils, and are the ideal carriers for all the chemical compounds used in mineral oils. Because they do not gel at very low temperatures, all genuine 0W-something oils have to be based on PAOs to pass the 0W test at a sub-arctic -35C.

Esters were originally made for jet engine lubricants, and to this day all jet oils are ester-based. Although similar in performance to PAOs, they have a valuable extra trick: they are good lubricants and help to protect metal surfaces. Esters help with transmission and valve train lubrication. 100% fully synthetic oils are actually quite rare, probably because they are very expensive to make, and even more expensive to buy.
Even so, an ester/PAO with a very shear stable multigrade polymer is the ultimate oil for high output engines that are worked hard, which means racing.

4) How does oil work? What gives it its lubricating properties? How does it ‘cling on’ to surfaces?

A plain bearing such as a main or big end, when spinning fast is ‘floating’ on a relatively thick film of oil. The metal surfaces literally do not touch. The high velocity drives a wedge of oil between the two surfaces, and the oil film supports the load, just like a water skier skimming over that very thin lubricant, water. But, when the engine slows down and stops the bearing shells drop through the film and touch the crankpins, just as the skier sinks in up to his neck when he lets go of the rope.

It is where there is metal to metal contact that lubrication, that is, something to reduce wear and seizure, is needed. On gear teeth, valve components, and piston rings at top or bottom dead centre, there is no high speed rotation to generate ‘wedge’ support, so the oil films are very thin, and some metal contact is inevitable. Some fluids, even if they look thick and oily, are completely hopeless! Very pure mineral oils, and some synthetics fall into this group. They depend entirely on chemical load-carrying compounds which react with metal at high pressures and temperatures to provide very thin protective films which prevent micro-welds where metal surfaces come into contact.

Detergent and antioxidant chemicals often double up as anti-wear agents. The odd ones out are esters. These are attracted to metal by electrostatic forces and cling on when surfaces are forced into contact.

5) What are (or can be) the main differences between oils of the same type, i.e. what’s the difference between a ‘good’ and a ‘bad’ oil?

It all comes down to honesty really…..so beware! A good oil is what it claims to be on the can. 10W/40? Does it really pass the cold test at -25C? Quite a few I’ve tested do not. There is usually an API spec quoted, such as API SH or SL. These are car-based, and a good basic quality guide. If absent, leave it on the shelf, and avoid lawyer-speak:
‘meets the requirements of….’ or ‘recommended (by whom?) for use in….’.

Then there is the ‘synthetic’ minefield! Provided the price hasn’t been pushed up by shipping an average oil 5000miles from the West coast of the USA, you get what you pay for. The best performance oils are made in the more developed European countries, but low price buys the cheap ‘modified mineral’ synthetic and not much of it, with a poor multigrade polymer. As is so often the case, quality follows cost.

6) What are the likely consequences of using poor-quality oil?

Usually, these are fairly long term, except in racing. Think of the oil as a liquid component, and poor oil as a cheap pattern spare. In a road car long-term reliability and performance retention (i.e. acceleration figures below new spec., fuel and oil consumption above) are the casualties. Particularly in a high performance or racing car,
the effects can be more immediate and catastrophic.

7) Some oil companies have run advertising campaigns that imply their products have special, unique qualities. Can these adverts be taken seriously?

Yes and no! Generally adverts in magazines are honest, with marketing-speak terms such as ‘Magnatec’ and ‘Electrosyntec’ really being code words for esters, which are particularly beneficial in performance engine oils. No manufacturer has any unique ‘secret’, so it’s all down to providing the best possible blend for the job at the right price, and making it clear that you get what you pay for. I personally think that the importance of shear stability or ‘stay in grade’ is not stressed enough when quality is talked about.

What is dodgy though is claiming that a mineral based oil with a few percent of modified mineral (‘hydrocracked’) synthetic is the DB’s and suitable for racing, etc. when it clearly isn’t.

Also, there is endless semantic manoeuvring and lawyer-speak around The Magic Word ’synthetic’.

For instance, a ‘synthetic’ oil is invariably semi-synthetic (’Ah! We didn’t say it was all synthetic did we?), and, if low priced, invariably the modified mineral type synthetic. It is a sad fact that you get what you pay for, but even so, stick to the reputable UK/European brands, and remember that shipping an oil half way around the world doesn’t automatically make it better than one made in your home town.

As for TV advertising…well, does anybody believe it? Due to its huge cost, a TV advertising campaign can significantly raise the cost of specialist items such as oil. Everybody assumes it’s just a few pence per gallon, but it can be pounds per gallon.)

Please can you explain the grading system? What is meant by the weight of an oil? What does 10W/40 mean for example?

Weight means viscosity, or resistance to flow. Water and paraffin flow very easily, so they are low or light viscosity. Golden syrup or 140 gear oil do not come out of the can so easily, so they are high or heavy viscosity.

Especially with oils, temperature is very, very important. An oil which looks ‘heavy’ at 20C will be very ‘light’ at 100C. People sometimes say, ‘I drained the oil when the engine was hot and it ran out like water…’ so I say, ‘Good! It’s supposed to be like that!’

The American Society of Automotive Engineers (SAE) ratings cover cold starts and ‘up and running’ viscosities. There are two sets of standards, the ‘Winter’ (W) ratings, and the 100C standard ratings. (‘W’ does not, repeat not, mean ‘weight’!)

So a 10W/40 oil has to pass a 10W cold viscosity test at -25C, and a SAE 40 test at 100C. In an oil lab there will be a refrigerated viscosity measuring device for the ‘W’ tests and another at 100C for the standard SAE tests. There are 6 ‘W’ ratings from the difficult 0W at -35C to the dead easy 25W at -10C, occasionally used in India for example!

The whole point of these Winter ratings is to assist cold starts, to get the oil circulating quickly, and to avoid power and fuel wasting drag as the engine warms up. Once it is warmed up, the 100C ratings count. There are 5 of these, 20, 30, 40, 50, and 60 although why anybody bothers with 60 in the 21st Century is a mystery to me!

Sorry folks, but I’ve got to get technical. Viscosity is measured in standard units called ‘Centistokes’, names after a Victorian engineer, Sir George Stokes, who used to time ball bearings as they sank through oil. SAE 30 for example is from 9.3 to 12.5 Centistokes, and SAE 40 follows on at 12.5 to 16.3, although most SAE 40 oils are in the middle at about 14.

Now this is something most don’t realise: engines do not know what grade of oil they’re running on. They’re not clever enough! So an engine filled with 10W/40 will be running on a viscosity of 14 at 100C, but with a sump temperature of 90C its seeing a viscosity of 18, so as far as the engine is concerned it’s running on SAE 50. Likewise, at 110C, it’s down to 11 Centistokes so it ‘thinks’ it’s on a SAE 30! (Which is preferable.)

The lesson is, do not use power and fuel-wasting thick oils in cool climates. A decent 10W/40 or even thinner is perfectly OK unless you’re running a classic with wide clearances and a slow oil pump.

Radical race cars use 1300 Suzuki Hyabusas and work them very hard. (Didn’t one take the old Nurburgring absolute record at one point?). They use our high-ester 15W/50, but that’s OK because they see oil temps around 130C! (No problem for the oil or the engine, but they do fit special oil seals.) At 130C the true viscosity is 10cSt, so the engine thinks its on a thin SAE 30, which keeps it happy.

What is the best type of oil to use in a road car for general use? Is fully synthetic a waste of money?

Personally I’d go for a shear-stable part ester synthetic, SAE 10W/40 or 5W/40. The ‘shear-stable’ bit (ie, a decent quality multigrade polymer) is actually more important than the ‘synthetic’ part!

If strapped, I’d go for a shear-stable mineral based oil rather than a ‘synthetic’ of dubious stability that’s probably based on modified mineral oil anyway. Unless you’re covering a huge annual mileage, genuine 100% synthetics are probably an extravagance. High mileage long-distance fans can use a light full synthetic and save on fuel and oil changes, and cut overhaul costs if things get to that stage, but more later…..

9) What are the main differences between 2 and 4-stroke oil? Why does 2-stroke oil have to be mixed with fuel?

2-stroke oil has a very short working life, straight in and out, and it gets burnt. The 2-stroke engine doesn’t have a sump full of oil and the bearings are all rollers, so there’s hardly any oil drag, hence no need for multigrades. Long term stability is obviously not a problem!

But, 2-stroke must burn off without leaving any plug-fouling or detonation-initiating deposits. The detergent and anti-wear additives used in 4-stroke oil leave hard white ash behind when they burn, just what you do not need in a 2-stroke. So 2-stroke oils use low-ash detergents and dispersants, and the better types use ester synthetics to act as anti-wear compounds.

With current environmental concerns, smoke is a sensitive issue, so most ‘road’ 2-stroke oils are now low smoke, which requires yet another type of synthetic base designed to burn off invisibly. For some rather basic but very high-revving air-cooled racing 2-strokes there’s still some sense in using blends with that marvellous anti-seize liquid, castor oil!

Due to crankcase induction and compression, the classical 2-stroke obviously cannot have an oil-filled sump, so the only way to keep an oil film on anything was to add oil to the fuel, or inject oil into the crankcase space where it could mix with the fuel vapour. There are now some engines where the fuel and oil are injected separately, but the oil is still burnt.

10) How important is it to change oil regularly? What are the implications of failing to do so?

It is only really important to change oil regularly if the engine covers a low annual mileage made up of slow, short runs. This is being cruel to the oil and the engine! The oil, regardless of its quality, gets full of fuel and water vapour, and never gets the chance to evaporate it all off with a long fast run. The consequences are corrosion, ring and bore wear. It is essential to do a change at least once a year, even if the recommended mileage hasn’t been covered. On the other hand, if you eat up the miles on long blasts the engine and its oil will love it, so with a top-quality oil it is OK to cheat a little on oil drain periods.

11) Do some types of oil (i.e. fully-synthetic) ‘wear out’ quicker than others? How important are timely oil changes? Can you rely on the frequency suggested by your User Manual?

The type of oil that is likely to give trouble after low mileage is a light viscosity type with poor shear stability, either mineral or modified mineral based. (Such as one of the USA ‘fuel economy’ oils for lazy car engines that pushed the Japanese OEMs to bring in their own oil spec.) The important thing is the shear stability; the much hyped ‘synthetic or mineral’ nonsense is a red herring.

The oils that will last the longest are the relatively rare 100% genuine synthetic shear stable types, which will easily stand twice the recommended drain period in a high-mileage high performance engine. (So in the long run they aren’t really so expensive.) Just the thing for those touring fiends who pack up and set of for the Transylvanian Alps as soon as the clocks go forward!

Of course, User Manual drain recommendations are based on a back-covering ‘worst case’ scenario of low annual mileage on poor quality oil, so they can be regarded as a very safe minimum mileage.

In the past, there used to be trouble with heavy carbon deposits and sludge around the engine with early low-detergent oils, but these days almost any oil with a good API specification will keep everything clean for 10 to 15,000 miles, so that’s the least of your worries.

12) Does oil have to be warm to do its job properly? Is it important to warm up your engine before using at speed?

Yes, it does have to be at least warm, and preferably hot. Most people except the sort with white finger syndrome find metal at 60C too hot to touch, yet 60C is too cold for oil in an engine that’s going flat-out. The best approach is to use a good 5W/40 or even a 10W/40, and take it easy for the first couple of miles, especially in very cold weather.
For racing, a really good warm-up is essential, except perhaps with special 0W/20 low-drag race oils. The trouble is, oil pumps are very good at pushing oil out at 60PSI, but unfortunately there is only 14PSI (atmospheric pressure) pushing it in! (Even less in Katmandhu.) So it’s easy for an oil pump to pull voids or pockets of vacuum in the oil if it doesn’t flow fast enough into to uptake. This ‘cavitation’ obviously reduces the amount of oil the pump can deliver.

Also, in high-speed bearings the oil can be too thick to keep up with the high rubbing speeds reached in modern engines so the ‘wedge’ or hydrodynamic’ effect breaks down. I know it goes against common sense (whatever that is) but the faster a bearing is turning the thinner the oil should be. (A 4cm. diameter main bearing is rubbing its shells at 56 MPH at 12,000RPM! To avoid cavitation the oil need to be less 10cSt or less, which is SAE 30 if the oil happens to be at 100C, or SAE 40 if its at 110C.))

What is the difference between road and racing oils?

The days of incense-like ‘R’ oils for racing only are past, except for classics. At least as far as 4-strokes are concerned, the best synthetic types are ideal for both race and road use.

With ultra-precise components, high-pressure pumps and high engine RPM there has been a move to special synthetic low cavitation/low drag oils to release more power with no reliability loss. These can be (and are!) used in road cars, but 0W/20 is not mentioned in the user handbooks, so there is always some warranty risk. Honda is perhaps the only exception!

13) How does a high-performance oil allow the motor to produce more power?

An engine wastes fuel energy in several ways, and most of them are due to the laws of thermodynamics, which is another way of saying you can’t do much about it. But up to 6% of engine output is lost due to oil drag, made up of pumping losses and viscous drag between moving components. The transmission is included in this.

Provided wear and friction are kept down, there are real gains to be made by using a ‘tough’ but low viscosity oil. Surprisingly, frictional losses are low, down at 3% or less even with conventional oils, so there are few gains to be made here.

I have actually seen this extra power output on the dyno! A very experienced operator in Peterborough who does a lot of test work for Lord Emap used his own year-old Honda Blackbird, with the first run on his favourite 15W/50 high-ester synthetic. 128BHP.

Then we changed to a 5W40 high ester synthetic. (So it wasn’t an unfair comparison with B & Q 15W/50!) This time we saw 131.6BHP with a corresponding torque increase.

Finally we went to a new (at that time) 0W/20 special synthetic and 134.4BHP appeared! Even the boss was impressed! Later trials in different race and road engines showed this level of improvement was no fluke, so it really does work; and, with the right chemistry to look after the engine and transmission internals, there’s no down side of increased wear.

14) Why do some engines consume oil? Is this a problem?

Large air-cooled engines or classics with wide piston clearances, or very highly stressed liquid-cooled engines which flex under load, or which use ultra-light pistons with the minimum number of rings are likely to be oil users. There is little that can be done about it. Unfortunately, burnt oil tends to leave hard deposits in the combustion chambers which can initiate pre-ignition, so more frequent top overhauls are usually necessary.
Occasionally, touring engines will use oil for no apparent reason. This is often due to the oil level rising in the crankcase due to air retention, leading to oil loss through the breather. The answer is to move to a lighter grade of oil to improve air release.

15) If you need to top up your engine oil, how important is it to use exactly the same brand and type?

Not very important at all. Unfortunately, due to ‘a**e covering’ reasons we cannot print this advice on the can! Although officially all manufacturers advise against mixing different makes and grades, in fact there is very little chance of any harm being done, even if one is a mineral 20W/50 and the other is a 5W/30 synthetic. Obviously, avoid this if you can, but do not panic if there’s no other alternative. Just don’t mix 2 stroke and 4-stroke oil!

16) There are all sorts of additives available which are supposed to improve ordinary oil and reduce friction, improve power output etc. Are they worth a try?

Oil is already a very advanced and deeply researched fluid which does not need any ‘enhancement’. There is no secret formula out in the backwoods that the mainstream lubricant chemists do not know about; but there are plenty of half-baked ideas and gullible people out there!

These wonder additives are usually 1930s chlorinated paraffins, long obsolete gear oil additives which should have disappeared in the 1950s, but they keep turning up as ‘Xxtrasuperlube ZX3’ with a mark-up of several thousand percent. They actually corrode engine and transmission internals, so they do far more harm than good.

Others depend upon the total myth that PTFE powder coats engine internals and reduces friction. It doesn’t do anything or the sort. It just blocks the oil filter. The AA tested one of these overpriced PTFE concoctions (‘Quick 60’ or something) very thoroughly back in the 80s. They stated: ‘This is an expensive way of coating your oil filter’.

Tedjs, our GM professori, emailed me a few photos of a modern Mass Air Flow sensor. He uses these shots for his automotive class at Tri-C in Ohio. I’ll attach his comments from my original post as well, as I think they’re quite relevant for anyone looking at a faulty AMM/MAF.

In these shots, you can clearly see the filament I was talking about. The object of the game is to keep that filament at a constant set temperature using an electrical current (think light bulbs). Air rushing past it cools the filament and the change in voltage required to keep it at temperature tells the computer how much air is rushing past, and therefore how much fuel to pump in.

Whilst my old 900 sensor had an adjustment screw, it seems that modern MAF’s don’t. A possible solution for a malfunctioning MAF, in the absence of an adjustment, is to clean it. Following are some comments Ted wrote about cleaning the sensor:

We would let the sensor cool off for a bit and hit the sensing wire with a quick shot of cleaner which is a key point here – a very small amount would clean the sensor if it was contaminated. I only say this because I watched someone use half a can on a sensor and I think it damaged the sensor as brake parts cleaner is a strong solvent. Unfortunately some people live with the adage if a little is good – a lot must be better. Don’t get me wrong – it was entertaining watching him, but that was kind of his method of operation. The guy could not fix a sandwich.

Sometimes if you would clean them the problem would come back and the sensor would have to be replaced. The sensor wire generally gets about 100 degrees Fahrenheit (37.78 degrees Celsius) higher than ambient air temperature so I think things would get cooked on it occasionally.

CRC recently introduced a mass air flow cleaner here in the USA that is for sale at most auto parts stores. It is less caustic than brake clean and is less likely to damage the sensor housing and attack the electronics. I know some shops are selling it as a maintenance service as newer cars are so reliable they have little to do in terms of routine maintenance, but I have mixed feelings about that. That sensor is expensive and cleaning a clean one might damage the filament. Sort of a ‘if it ain’t broke – don’t fix it’ approach if you know what I mean.

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Inspired by my successful venture yesterday and a desire to learn more, I’ve just ordered a Bentley manual for the Saab 900 16V to go with my Haynes manual that’s already on it’s way from Elkparts.

The Bentley manual seems to be pretty well regarded, so I’m sure it won’t hurt to have it on the shelf as well. There’s probably areas of the car that one manual handles better than the other.

I don’t think I’m going to be replacing timing chains or anything like that, any time soon. But it’s fun to learn, especially with our young bloke hitting 17 and looking for a car to buy too (He’s scoping out Honda Preludes).

He’s got a natural aptitude for this sort of thing so I’ve got to keep up!!

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Some of you may recall that I had some issues late last year with my 1985 Saab 900 Aero. The car would develop this tendency to jerk around a lot.

At first, we thought it was the fuel pump playing up, but $400 and a replacement later, we learned that wasn’t the case. Matt the fudgepacker correctly diagnosed the problem as being the Air Mass Meter. These are pretty expensive to buy new (around $800 here in Oz) so any sort of fix would do. Matt provided the simplest answer possible – A quick tap on the head of the unit and it seemed to right itself. It worked on the odd occasion it was needed after that, so I didn’t worry too much.

The problem was long forgotten until earlier this week, when the car developed it’s jerkiness once again and no amount of tapping on the AMM would set it straight.

Hesitating to pony up for a new unit, I rang a spare parts supplier in Melbourne and got them to ship over what they thought was a good second hand unit. I fitted the unit to the car today and it ran even worse than when I had my old part on it. Here’s the part, so you know what it looks like:

That’s actually upside down to how you see it in your engine bay, but the battery ran out in my camera before I could take another shot

So whilst my part was off the car, I thought I’d take it into my local Saab specialist, Steve E, so that he could have a look. Steve tested the unit and found it had been adjusted at some point. Once it was adjusted back to the proper settings, I took it home, reinstalled it, and now the car’s running as good as gold.

So what was the adjustment?

Here’s a look at the unit from a different angle:

As you can see, there’s six pins in the plug for this unit. The test involved putting a multimeter on pins 3 and 6 and measuring the ohms. It should read 380 ohms. Mine was reading somewhere up past 530 ohms. The supposedly good replacement part I got from Melbourne was reading 995 ohms!!

You can see a gold-colored adjusting screw just to the right of the plug in that photo. That screw adjusts whatever it is that adjusts the ohms readout. Steve simply turned the adjusting screw until it read 380 on the multimeter.

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How the AMM works (my limited understanding) – the computer sends a current through a filament in the AMM, which is cooled by the air passing it. If there’s more air passing by and cooling the filament (and going on into the engine) then the AMM boosts the current in order to maintain a set temperature in the filament. The variations in current required tell the computers how much air is coming into the engine and therefore, how much fuel is needed to match the air and create an optimum mix.

I assume that if there was an incorrect setting, such as that on my unit (where it was 500+ ohms instead of 380), then it would be misreading the volume of air that it’s meant to measure, hence the rough running that I was experiencing from time to time.

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I believe the AMM is also commonly referred to as the Mass Air Flow sensor (or MAF)

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The theory here is that once you wrap your exhaust manifold in this heat-absorbant bandage, it retains a lot of heat in your exhaust headers instead of radiating it into the engine bay. The result is a quicker evacuation of exhaust gases from the combustion chamber, as well as reduced heat in your engine bay.

The reduction in ambient heat is supposed to be of benefit (especially to turbocharged engines) because cold air is denser and you can therefore get more punch from your turbo by keeping the air temp down (which is why we have intercoolers, water injection and cold air intakes – they’re all trying to do the same thing). The other advantage in some cars will be the reduced possibility of damage to heat sensitive parts, wiring etc.

Here’s what the finished product looks like (not a Saab manifold):

The bandage is quite thick and the whole process is a) relatively expensive at around $80 for 100 feet of tape, b) time consuming, and c) awkward. You have to try and wrap the entire manifold and tight spots can be a pain in the backside.

As mentioned, I’ve got a wrapped exhaust on my 1985 Saab 900, however I’d be interested to hear the thoughts of others who have done this. My exhaust was already wrapped before I bought it, so I don’t have a before/after experience to relate here.

If you’ve wrapped your exhaust, did you find that it had any effect of the performance of your car, even if it’s just keeping temperatures down a bit rather than a noticeable performance gain? Even a small effect?

Did you think it was worth the time/money/effort?

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There’s a quick piece on the process of wrapping one’s exhaust here.

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I’ve never purchased a brand new car, so I’ve never had to think about running in a brand new engine. Those of you that have may want to share your knowledge with Shyang, who asked the following via email:

I am about to take delivery of a new Saab and I am hoping that you can help me. I was wondering if you have any guides that will teach me to properly run in a new engine? I intend to keep my Saab for at least 10 years and I have heard that the difference between a properly run in engine and one that is not is quite noticeable in the later years.

I have searched online and there are quite a lot of different methods. Some examples of what I have found:

Some recommend running the engine hard through all the different gears to ensure that the seals sit properly and then changing the oil right after, about 100km.

Some recommend not pushing the engine too hard, to keep it under a certain rev and not to go past a certain speed until 1000 – 2000km.

Some recommend using mineral oil for the first 1000km then changing to synthetic after.

Some recommend changing the oil at 1000km and then again at 5000km.

Some recommend not changing the oil until at least 3000km.

Some recommend that the engine has already been run in at the factory and the car should be driven normally from day 1.

As you can see, some of the run in methods can coexist but most don’t and they may even contradict each other.

So – new car buyers…….please fire away with your thoughts, experience and advice in comments.

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