Originally Posted By: RI_RS4
After having the previous valve deposits issues running Audi approved oils, SilverRS4 took matters into his own hands by changing to Biosyn 5W40 and BioPlus, along with pulling the intake manifold to view the intake valves on a regular basis. Here are his results:
Quote:
I had the manifold off the fourth time about a month ago when there was close to 3000 miles on the Biosyn. The valves were not clean, but it was more of a thin, oxidized film of oil, rather than thick, gooey, flow-blocking black crud (which was the case after 4000 miles of factory oil, 4000 miles of Mobil 1, and less than 1000 miles of Castrol TXT). I was pleased and will certainly keep using the Biosyn. I am sure Scott could fill you in on the chemistry that makes the build up rate noticably less. I also use the Biosyn fuel conditioner (2 oz) with each fuel fill of Shell gasoline to make sure the injectors stay clean. With the FSI aspect of the 4.2L engine, I believe that sparkly clean valves is just not a realistic expectation - even with Biosyn. But I am happy with how its working thus far. The aspect that really hasn't been discussed is the affect that the oil "contaminated" intake charge has on optimum spark timing. The advanced RS4 ECM's and knock sensors seem particularly sensitive. After endless logging, I have a few cylinders that have timing retarded 4-6 degrees under moderate loads and 9-11 degrees under heavy loads. That is significant. I live in the Midwest and am stuck with Ethanol blended fuel even in the 91-92 octane Tier 1 fuels (Shell included)- that could be part of it, I don't know.
As far as my cleaning method, it was just the old fashion way. In six of the eight cylinders, the intake valves were completely closed, so I just poured in several ounces of carb cleaner right into the intake ports and let the valves soak several hours. Then a majority of the crud comes off with aggressive scraping with an appropriately shaped metal tool. The valve stems block the ability to scrape the area behind them. Vacuum out the mess. Then I poured in fresh solvent and put a small Dremel-type wire brush tool on the end of a cordless drill. Scrub, scrub, scrub. The varnish layer of buildup on the valve surface is very, very hard. This method is limited and removes 90% of the build up at best. The walnut shell blasting would be far better. I have access to such blasting equipment and media, but its ridiculous that I or anyone else has to consider such a chore ...warranty work or not.
If this is not part of the regular scheduled maintenance and I bought this car, I would find an attorney and sue Audi for a refund. The car has a serious defect and no one should have to put up with that.
