nyet

In the end, most of the deposits come from oil coking, exacerbated by soot from combustion.

Whether or not a change in oil composition will help matters is beyond my expertise. I believe that is what you are arguing, not that deposits are NOT from blowby oil in the intake.

silverRS4

You've never given Audi techs a good rap, why now? They shrug it off. Especially after people change to Tier 1 fuel(if they weren't using it already)and swear they drive it hard frequently and the problem persists. Nobody here is denying that some combustion related carbon-based deposits can find their way up the intake stream. But to take an engine like the 4.2 FSI, which volatizes oil at a high rate, has a high amount of oil vapor in the crankcase airstream and can have deposits on the intake valves that looks more like wet sludge (it doesn't get wet from fuel now does it?), not sooty flakes, and say that oil is not a fair portion of the buildup is absurd. I won't speak for Italian motorcycles, ATV's, or S4's because I don't own them and haven't tore into those engines, but here's what happens on some RS4's. Build up accumulates on the intake valves and/or combustion chamber. Particles of this buildup eventually interfere with the injectors, affecting their spray characteristics, or at worst, cause them to leak under residual fuel pressure. When the engine is off, the faulty injector(s) leak fuel into the combustion chamber, creating an abundance of fuel at startup and a misfire in that cylinder. Since the misfire is not coil related, the engine just runs rough for a while, then appears to run ok. The misfire code has been thrown, however, so the dealer happily replaces your coil(s). Once this happens 3 or more times, the same dealer who asks you what gas you use and how you drive the car, may figure out its not a coil related issue. There are way too many threads on this forums with similar symptoms to say this has only happened to a couple of RS4s. Yes, if you goose the throttle occasionally and drive the car hard, you'll clean out some soot and combustion related buildup, most of which dislodges from areas downstream of the intake valves. But until the amount of oil volatization in the RS4 engine can be reduced, intake valve buildup will be a problem. Your opinion is that oil chemistry has nothing to do with the buildup. OK, I get that. Maybe no oil formula will help the problem. There are plenty of technical reports on intake valve buildup and direct injected engines. A fair amount are written by people in the oil industry - not Harley Davidson, Kawasaki or Aprilla.

daveak05

My point has been all along that changing from one high quality synthetic oil to another isn't going to solve a problem of this kind, at this level.

Nicht ein A4

the whole oil breather thing was something I pulled out of my **** for discussion. No one, repeat NO ONE at Audi claimed it was oil.

Nicht ein A4

when I bring it in and they take a look in the intake runners/valves and see if carbon build up is the problem again. As it was the problem in the first 7K miles and is now back again with the same symptoms, I suspect it to be the case again.

I will keep you posted.

daveak05

it's a starting point. I just truly don't believe the oil even begins to explain the problem...not in 2k miles.

daveak05

I agree, what else can you do at this point? Good luck.

RI A6

First he said that it could not be the oil causing the intake valve deposits whatsoever.

Now he says it could be the oil causing the deposits, but it must be due to something else that is wrong with the engine (... not withstanding the fact that this intake valve deposit formation problem is happening across all Audi FSI engine models ...) and that there is no value in using a different oil. (i.e. - all good synthetic oils are essentially identical.)

daveak05

That's just BS. I've said all along that using a different oil(your oil) cannot explain what people are experiencing with this level of carbon buildup so quickly. You'd rather continuing arguing that by focusing only on the oil and mischaracterizing what I say every step of the way. It's absurd and so has been your whole argument.

You're dreaming if you really think that switching to BioSyn will take care of this. The ultimate in naive.