I am 1100 miles into the rinse cycle after a two bottle, over 100,000 mile, cleaning with auto-rx. I have used Castrol GTX 10w30 conventional for both cleaning cycles, as well as the current rinse cycle. Previously to the auto-rx cleaning I was using Mobil 1 10W30. My car is a 1990 Mazda Miata with over 222,000 miles. My idle speed was always rock solid at 850 rpm. During the rinse cycle it is at 1000 rpm. Is this due to the engine being cleaner and better lubricated now? That is what I suspect. My engine is running strong and smooth, just at a higher idle speed. Thanks in advance for your comments.