richard-tx

That is not the whole story. The lighter weight oils like 0w and 5 w are used so that the oil will be flung far and wide thus lubricating things like cams and lifters quickly at startup. I saw what happens when something like straight 20w50 is used in a modern Audi engine that specifies 5w oil. The cam shaft lobes were flattened out.

The other part of the story is that the internal clearances are much tighter than they used to be. If the oil is too thick, various parts will wear prematurely. In short, there is a fair amount of "splash" or indirect lubrication occurring in the late Audi engines. Reduce the amount of oil getting past the journals and the amount of oil available for indirect lubrication is reduced.

winy68

thanks to everyone for your informative replies.

Even in my hot climate, I guess I'll start using 0W-30. If for no other reason than to appease the Audi gods

If anyone's interested... Here's a list of 0W-30 502 00. that are available on amazon. I dont think Mobil 1 or Kendall make 0w30 502 compliant. Not sure if I missed any.

Redline - $12 a quart
castrol edge syntec - $9 a qt.
Motul 8100 - $80 (5 liter bottle)
Liqui-Molly - $50 (5 liter bottle)


thanks to Mishar for redline tip and
The Duke, Richard-tx for liqui-molly tip and
Rhouse for castrol tip

richard-tx

Napa has LiquiMoly or can order it for you.

Rhouse181

Let's delve deeper...

The use of 20w oil alone did not ruin camshafts. Was this a nice fully synthetic 20w50, or dino oil? Was this oil changed at regular intervals, or left in the motor for 50k without changing? More information is necessary before we can draw any causal relationship between 20w startup viscosity and ruined cams. These motors use roller rocker arms and not flat tappets too... you have to work really really hard to wear down cam lobes with roller rockers.

So called "splash" is the enemy of engine design. Splash creates aeration in the oil, which compromises lubricity and contributes to premature wear. Oil control, whether it be at startup or during normal operating temps, 100% does not rely on any form of splash lubrication.

Audi went out of their way to design the 4.2 to reduce aeration and avoid crank splash. Here are some quotes from the 4.2 SSP:

"The focal point of development was on significant
reduction of the oil flow rate. As a result, the oil remains
in the sump longer and is better able to de-aerate."

and

"The baffle plate is designed such that it not only prevents
the crankshaft from churning the oil in the sump, but also
strengthens the main bearing walls."

EHLO

Please do, any information helpful in avoiding FSI carbon buildup is appreciated, thanks.

MP4.2+6.0

You are paying a lot these days... If you go to 0W40, you can get either Mobil 1 or Castrol Euro Formula in 5 quart jugs from Amazon Prime for $23 or $26-- +/- $5/qt.

You are correct. Mobil 1 in 0W30 (or 5W30 or a variety of others) is not 502 compliant. In Castrol, the ones commonly found in US retail channels that are labelled European Formula as well as the 5W40 are compliant. Both the Mobil 1 0W40 and Castrol 0W30 also met the old 503 spec used for the D3 W12 in Europe at introduction, so I like that. I have used the Castrol 0W-30 in our Mini regularly, since Mini/BMW spec a 5W30 max viscosity oil for them and it also meets the BMW long life spec relevant there.

MP4.2+6.0

From having had the lower pan off and pulling a con rod and piston assembly from my 2000 A6 4.2, I can validate first person this is true. The baffle plate is in there and separates the crank pretty thoroughly from the lower pan; made getting at con rod bolts more challenging than prior Audi motors I have been in. They also don't need splash, since they have had the oil jets under each piston for quite a while now, my 2000 included. The whole intermediate oil sump and integrated mains set up holds crank somewhat higher too. There is also the oil screen down under the intake before the PCV valve on ports, and the yet more thorough filtering system on W12's and I think on 4.2 and S8 FSI's.

Rhouse181

OP, apologize for hijacking your thread here but I nerded out on this stuff when the 2.0T FSI motors first came out in the GTIs.

In Europe, the ECU uses injection cycles called "lean stratified charge" which essentially shapes the gas vapors in the middle of the cylinder to improve efficiency under low load conditions. This ultra lean mixture leaves no fuel for oxygen to react with so it mixes with nitrogen instead. This results in elevated NOx levels which need special catalysts to comply with emission standards. Unfortunately, these catalysts get easily poisoned with higher sulfur content in fuels.

North America gasoline "had" higher sulfur content compared to Europe, so when VW / Audi paired this lean stratified charge with NA catalysts they experienced high catalyst failure rates and reduced lifetimes. Instead of redesigning lean stratified charge for the NA market, it was more cost effective to just ditch it completely and run a more rich homogeneous injection pattern to keep NOx in check.

Combustion chambers and piston crown design and injector geometry were all designed to accommodate these lean run conditions. Without lean stratified charge, more fuel washes against the cylinder walls. As the pistons go up and down, they scrap this access fuel into the crankcase. This fuel mixes with the oil, decreasing the oil's flash point (or temperature that the oil vaporizes) and increases the oil's volatility. More volatile oil increases the amount of crankcase vapor which then gets recycled by the secondary air system back through the intake system to be re-burned. The venturi filters on these crankcase recycle streams weren't designed to handle this level of vapor content. Therefore you get oil laden air washing across the valves and major oil build up issues.

There is no elegant solution to the issue, but you can use higher quality polyol ester based oils that are more effective at withstanding volatility increases. And most importantly... ignore VW / Audi's ridiculous 10k oil change intervals! No oil can withstand it's chemical properties over these lifecycles.

mishar

Are you saying that North American FSI engines actually are not FSI (Fuel Stratified Injection)?

I would rather not. Most of A8's (and others) do not have carbon deposit problem. Changing oil more often is just waste of time and money. Also bad for environment.

Rhouse181

Not at all. The stratified in the FSI nomenclature is true for all FSI motors worldwide. Fuel-air mixture is essentially fixed and the direction injection system "stratifies" or regulates the amount of fuel through pressure adjustments to maintain the desired ratio.

North America does not receive the ultra lean burn mode, or "lean stratified charge."

Early DI across almost all manufactures experienced carbon buildup issues, especially in North America. Toyota was smart because they chose to combine both port injection and DI into one package. But any VAG motor with DI has carbon buildup. I would also be the first to admit that the degradation in performance for the majority of owners is deemed acceptable or not noticeable. The "sky is falling" aversion to DI is overstated.

I'm not here to argue with anyone about OCIs. I'm just sharing the information I found when researching this issue. I've done my own sampling and research to develop my opinion, but everyone else can decide for themselves.