JMH, I understand you skepticism. Unfortunately, with limited resources and an engine that is potentially destroying itself on Audi 502.00 approved oils, I couldn't wait another year, and felt I needed to take action. Other oil analysis results are slowly coming in from other engines, which will eventually put this concern of yours to rest.
If we take Fe wear off the table, then we can certainly agree that ring pack/cylinder system is substantially through the break-in region, can't we? If we also agree that a primary cause of fuel dilution is blow-by and fuel wash down, then we can hypothesize that we might be able to design an oil that better retards fuel wash-down and/or blow by, and better withstands the effects of fuel, than the 502.00 oils we are aware of. And, if we were to do this, we should be able to measure the impact on flashpoint.
Flashpoint is particularly interesting, since we have measured flashpoint that have dropped down into the average operating temperature of the oil in this engine. Normal oil temperatures in this engine run from 200F to around 235F under hard driving. Certainly, localized oil temperatures will be even higher. My concern is excessive oil burning, valve and combustion chamber deposit formation, as the oil breaks down.
We have several points of anecdotal evidence that there is a problem. First, several owners (realize there are only 1200 of these cars in the US) have noticed that oil consumption increases significantly after several thousand miles on the oil, in a step-wise fashion. (i.e. no oil consumption and then suddenly 1 Qt is burned.) In one case we were able to convince the owner to test his oil and found that flashpoint had dropped to 230F, with fuel dilution measured > 2%. Second, at least one engine in the US has been diagnosed with valve deposits causing misfires, and other FSI engines (V6,V8 non high-performance) have been seen with the same diagnosis.
Personally, I've seen the following progression in my engine, with normal highway driving while on a long trip:
Mileage Mileage-on-Oil 40C cSt 100C cSt Flashpoint
Motul Etech 0W-40 VOA .. 72.0 .. 11.8 ...... 430
9510 .......... 537 .... 62.8 .. 11.9 ...... 270
10059 ........ 1086 .... 65.9 .. 12.4 ...... 280
10606 ........ 1633 .... 63.8 .. 11.6 ...... 270
11896 ........ 2923 .... 50.2 .,. 9.9 ...... 235
Other oils measured in different RS4 engines seem to show a similar progression, although we do not have as many intermediate points, we do have significantly low flashpoint over time of 275, 265, 250, 235, 230 and 220F. You will be hard pressed to find many UOAs on BITOG that show such low flashpoint on a new engines.
Upon switching to the new test oils I have seen the following progression:
Mileage Mileage-on-Oil 40C cSt 100C cSt Flashpoint
Test Oil 2 VOA ........... xx .. xxxx ...... 395
14779 ........ 1562 .... xxxx .. xxxx ...... 340 (Test oil 1)
15738 ......... 672 .... 79.0 .. 13.6 ...... 360 (Test oil 2 start)
16554 ........ 1488 .... 78.5 .. 13.8 ...... 345
18061 ........ 2995 .... 76.7 .. 13.3 ...... 320
Clearly the test oils are doing something. Couple this with what I suggest is a significant reduction in Fe wear, and we think we are on the correct path.
