S2 Engine Oil

[PeteRR]

A 0W-20 or similar grades should not be put anywhere near these engines. Those grades are for ultra-modern, super-tight toleranced, high-revving small capacity engines.
It has no place on a 80's designed, 2Litre+, Turbo 5 pot engine.

The manual for my car (RR engine ur-quattro) states the use of 5W-30 (if you are in the Artic!) to a 20W-50, i.e. a very robust engine.
They would originally have probably used a 10W-40 or 15W-40.
The RS exceeds the 'SJ' rating, but does not state the VAG spec. but lots of unsuitable oils do (e.g. 0W-30's).

RS is not too thick, the viscosity is the 'stickyness' of the oil rather than thickness. So the 60 grade clings to v.hot components better than lesser grades.

I initially used Synta Gold 5W-40, until I revved the engine after sitting in traffic on a super hot day and the oil light blinked on for a second on the overrun.
I changed to Castrol RS the next day, never a problem since and the engine now sounds a lot happier.

[Jamo]

A 0W-20 or similar grades should not be put anywhere near these engines. Those grades are for ultra-modern, super-tight toleranced, high-revving small capacity engines.
It has no place on a 80's designed, 2Litre+, Turbo 5 pot engine.

The manual for my car (RR engine ur-quattro) states the use of 5W-30 (if you are in the Artic!) to a 20W-50, i.e. a very robust engine.
They would originally have probably used a 10W-40 or 15W-40.
The RS exceeds the 'SJ' rating, but does not state the VAG spec. but lots of unsuitable oils do (e.g. 0W-30's).

RS is not too thick, the viscosity is the 'stickyness' of the oil rather than thickness. So the 60 grade clings to v.hot components better than lesser grades.

I initially used Synta Gold 5W-40, until I revved the engine after sitting in traffic on a super hot day and the oil light blinked on for a second on the overrun.
I changed to Castrol RS the next day, never a problem since and the engine now sounds a lot happier.

And this is where the problem lies, theoretically vs practicality.

In theory 10W40 or 5W40 is the stuff to use but practicality has shown that 10W60 be it millers or Castrol RS is providing the best results.

Let the debate continue as some of the stuff being posted is good reading.

[dan_b]

My car I think now definitely runs at a higher stable idle pressure with the 10/60 vs. the 10/40 Synta Gold. It does also seem to run a little hotter in all traffic scenarios than before - water temp indicator always on the hot side of 90, oil temp around 90 in slow traffic.

Don't know if that's all good or not? My reason for changing was the way my oil was behaving at the track day - I was seeing scary high oil temps, very low idle pressures, and actually the car started blowing oil a bit of oil when off-throttle (gear changes). Certainly the engine got very stressed that day: track temps were very high and it was a very fast circuit, and I don't think the 10/40 stuff was up to the job.

The problem is that it's very difficult for us to do a proper controlled experiment. We have old engines (both in design, and in physical age): we have all abused our engines to some degree or another. Engine tech, and oil tech, has changed a lot.

I'm tending to believe that the Castrol RS 10/60 is better than 10/40, but I have no proof. If someone can prove it - has the knowledge of the engineering and the chemistry, great!

[Pete_RS2]

Someone mentioned using Magnatec. I would only recomend this if 'Driving Miss Daisy' to church daily in their S2. I wouldn't let Magnatec anywhere near my turbo when its glowing red during a thrash. It was fine in my Golf 1.3 many years ago but not sure I would use it in anything much more highly stressed than that.

What's wrong with Magnatec then ? I used it exclusively for 2 years/40,000 miles in my S2 and it meets all the VAG specs in the handbook. No Miss Daisy or church either

[quattroboy]

They also list a CFS 15/60 Full Synthetic @ £32.00/5 litres

I spoke to one of their Development Chemists a few weeks back, he agreed 5W/40 was too thin and 10W-60 (Millers CFS or Castrol RS) was the best choice for these engines

[audiman]

These old engines were not designed for the modern type of oils we have today. I suspect that the cars never even used to run on semi-synthetic oils in the early days of the 3B. There will always be a right and a wrong oil, but smetimes there is a comfortable comprimise.

So WTF is it????

[Lee]

I am sticking with my Millers CFS 10W60 wherever this thread goes. I have discussed it with lubricant experts and my mind won't be swayed.

@Pete, I thrash my car every day, it has covered over 150k miles, it gets thrashed from cold and is never cooled down, it is running a K24 (still the original one) with too much boost and I have never had a mechanical issue. My afterrun pump doesn't work either. If I had used Magnatec or any other semi-synthetic oil I am sure it would have baked in the turbo by now.

I only use decent full synthetic oil and complete frequent changes.

Do you guys trust VAGs recommendations on oils? A company that now has service intervals of up to 20k miles on some of its cars? That is definately not a recommendation in the interest of engine longevity. They just want us to buy more cars more often..yes I am a very synical person but I also know how marketing and engineering combine to produce the products we buy. Do you honestly think they want cars to last forever?

Our cars are largely owned now by enthusiasts who now spank them on the track. Many owners have also increased their outputs by 100% or more. The days of company directors pootling around in these beasts is long over (I would have thought). Higher than standard bearing loads at a much higher duty cycle than any engineer would estimate for such a car demands a very high quality oil, designed for the high stresses and temperatures.

[Jay]

I am sticking with my Millers CFS 10W60 wherever this thread goes. I have discussed it with lubricant experts and my mind won't be swayed.

@Pete, I thrash my car every day, it has covered over 150k miles, it gets thrashed from cold and is never cooled down, it is running a K24 (still the original one) with too much boost and I have never had a mechanical issue. My afterrun pump doesn't work either. If I had used Magnatec or any other semi-synthetic oil I am sure it would have baked in the turbo by now.

I only use decent full synthetic oil and complete frequent changes.

Do you guys trust VAGs recommendations on oils? A company that now has service intervals of up to 20k miles on some of its cars? That is definately not a recommendation in the interest of engine longevity. They just want us to buy more cars more often..yes I am a very synical person but I also know how marketing and engineering combine to produce the products we buy. Do you honestly think they want cars to last forever?

Our cars are largely owned now by enthusiasts who now spank them on the track. Many owners have also increased their outputs by 100% or more. The days of company directors pootling around in these beasts is long over (I would have thought). Higher than standard bearing loads at a much higher duty cycle than any engineer would estimate for such a car demands a very high quality oil, designed for the high stresses and temperatures.

Bearing loads are not the issue, most oils are up to this. Upping the output of a turbo engine as long as you dont up the rpm limit doesnt increase loads as much as you would think (lots of science in this-may go into this later), but termal loads do increase massivelly so oil and cooling sytem, piston crowns, combustion chambers, valves and plugs can suffer if not up-graded or controlled properly (e.g big I/C etc)

With regard loads the cam 'ramp' or contact patch see the highest load and this is an issue at very high temp and rpm or if you use 'high' lift cams (steeper ramps, higher loads)

On our engines its the turbo temps that cook the chemicals in the oil combined with fuel wash and combustion by-products contaminating the oil causing varnises to build on the turbo bearing reducing clearances and restricting oil supply (not good on something spinning at over 120000 rpm) agian buy the best you can afford and change as often as poss

Also the cam chain running the inlet cam shears the polmer chains reducing its ablity to change viscousity. (viscousity is the resistance to flow, water flows quickly- trecle slow)

Once the oil starts to break down it repidly accelorates and the damage is irreverseable- have you tried to remove varnise ( black/brown coating) in engines, you need a acid to do it properly!!! these coatings stop heat transfer paths so piston crown and combustion temps rise- not good in a turbo car.

Jay

[Lee]

I guess we could go into all of the detailed IC engine dynamics, hydrodynamic forces, viscosity changes and tribology science (etc etc) here in great detail if anyone wants but it is going to get awefully technnical very quickly. The thread will become 100 pages long and all but 2 or 3 people will actively participate (the rest will have switched off). My degree was heavily based on dynamics especially IC Engines and I studied tribology during my time in the Space Industry working on mechanisms but that was not based on the temperatures involved in IC engines. I am not a chemistry expert but I am sure there are many here who can present the science involved in the breakdown of the chemical agents in the chains of PAOs, Ester synthetics, polymers etc found in modern lubricants. Where will all this discussion take us? I doubt that an intensive discussion on tribological science will tell the reader whether 10W40 is more suitable than 10W60, or that brand X is better than brand Y because we simply do not have enough data to hand. Tribology in IC engines is still a massive area for research and developement and new papers on the subject are popping up all the time so I doubt any conclusion will be reached here very quickly.

The answer is surely, use the best fully synthetic oil, change it frequently and don't skimp on price. If your oil temps have reached high temperatures, change it quickly and address your oil cooling (or buy a better oil!). I think we can all agree to that, but I think most of us agree that was common sense practice anyway.

[4WheelDrifter]

I agree. The latest oil technology is kept secret anyway, like most of the petrochemical industry. So it would be impossible to compare oils on a chemical and molecular basis to prove which was better, X or Y.

[Jay]

the answer

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I agree. The latest oil technology is kept secret anyway, like most of the petrochemical industry. So it would be impossible to compare oils on a chemical and molecular basis to prove which was better, X or Y.

I think we are all desided then, with all our collective brains there is one singular answer.................................ITS ALL WITCH CRAFT

Jay

[Fat Audi 80]

So which Bloody Oil do I buy. I must admit I spend the whole of my journey home thinking about MikeS2's post on the limitations of a 10w60 oil and its potential effects.

The conclusion I came to was, once the oil is hot there is little difference in the viscosity of that and say a similar 10w40 oil. It is the thickness at start up that could be a problem.

Personally I watch my oil pressure gauge like a hawk (I guess was as a result of having a very high mile Audi 80 with an oil pressure gauge) so I know it always bounces to the top on first crank every time. I am happy that this thicker 10w60 is hanging aroud in the engine and turbo protecting it more than say a thinner oil. There may be some higher running temps but I rarely see my oil over the 110 / 120 deg mark.

In conclusion I am sticking with Lee Milnea and others and will continue to use Castrol 10W60 unless someone can catagorically dispute this...

Cheers,

Steve.

edited cos i kant spel

[dan_b]

Ok - what about the Mobil1 5/50 oil?
Not as thick at the 10/60, but protection to lower temperature? Or is this not right either?

[Keeper of The Kitten]

Spoke to Simon (a colleague at work) - he's built lots of engines in his time for various folk, including Hart - and heaps of Palmer Audi 1.8t lumps (they had a full season of thrashing with no failures whatsoever). He says RS if you like, but Magnatec is fine - and don't waste your time changing oil more often than 6,000 miles unless you like buying oil (which the oil companies like you to do). I've used Magnatec since day one and experienced no problems. Ok, my car only sees fast road thrashing (but that includes 200 mile+ jaunts on very hot days), so maybe opinions will differ here. In fact, opinions will definitely differ here!

__MDC__

[Lee]

My oil comes out pretty dark if I leave it in there for more than 6000miles. Not cooling the car down doesn't help at all! That carbon particulate suspended in the oil after being baked in the turbo is like grinding paste so I will stick to my frequent changes and use a high quality synthetic to reduce the damage to the oil caused by thos high turbo temps.

Agreed, this is a public Forum so very full of opinions. Go with what is most comfortable for you (or whoever you trust) and if unsure see what others are comfortable with, close your eyes, chant "eeny meeny miny mo" and there you go...decision made!! On here you will only get a consensus of opinion on subjects like this due to the vast unknowns. The only way to be sure would be to have a dyno cell simulating the lifetime of the engine testing the various oils and that isn't really practical for most of us!