Today, I replaced my valve cover gaskets on my 89 Acura Legend with close to 200,000 miles on it. The engine is smooth as an electric motor and does not consume oil anymore. It is now in the second rinse phase of AutoRX. The first clean cycle was followed by a quick rinse of 1,000 kms and then another long rinse of 4500 kms. The second AutoRX treatment was also 4500 kms. ( I made a trip to the west coast and back) When I removed my valve cover gaskets I could not believe my eyes! The engine was still filthy. The valve covers needed major cleaning with solvents and a small stainless steel brush. I thought AutoRX was supposed to "break" this down. Furthermore since 12 years ago, this auto has had the 5,000km or 3 months routine pretty much all the time. I never expected this. Don't get me wrong, Auto-RX has smooth out the engine and it is now much quieter ( my lifters never ticked before either). What I noticed was that the front portion of the V6 had a lot of "grit" and carbon and was a dark red brown. The rear bank however had a golden patina and was much cleaner. Why was there a drastic difference in the way deposits and sludge builds up on this engine??? or a tranverse V6. All I can think of is the difference in cooling between the banks.