I have a 1998 vw passat 1.8t with 98,000 miles (bought at 77,000) and have been using Mobile 1 synthetic since I got the car about 2 years ago. My car runs smooth and the engine is so quiet that I can barely hear it on when I am idleing so I don't think I am in too much trouble but when I take off my valve cap things are very black.
What I really want to know is if I can buy Auto-RX and keep using my Mobile 1 but maybe change oil at 2-3k instead of 5k?
Think you should seriously consider doing a full Auto-Rx Sludge Application. Please read the FAQ and get a good foundation of why we prefer no group 5 synthetic in sludge removal. Passatt is anice car and we can help it stay that way.
Once you have completed your Auto-Rx application, you can continue using your synthetic oil with a maintenance dose of Auto-Rx. However, for your Auto-Rx application, stick with a Group III if you must use a synthetic. Mineral oil, however, is strongly recommended.
Auto-Rx is actually a much more efficient way of cleaning your engine than taking it a part. That said, as your vehicle's nearing the 100,000 mile mark, you might want to consider two applications.
Use any number of 5w-40 or 15w-40 oils for your VW. Rotella T synthetic 5w-40 is perfectly fine for Auto-Rx ..as would any of the HDEO (mixed fleet) oils. The main thing is that you're not going to have them in service too long anyway, so the oil selection issue doesn't have to pass any endurance test or economy test (the 50X.xx garbage).
Patience is the key here. Stay the course and you'll clean up the mess sooner or later.
