If you want to get the best cleaning results with Auto-Rx, you will need to run it in conjuncture with a group III synthetic oil. Group III is a highly refined mineral oil, to the point whereby it can be labeled synthetic, here in the States. Castrol Syntec and Pennzoil Platinum are two examples of group III oils that Auto-Rx cleans and rinses with very well.
To accomplish the greatest cleaning level, we dont recommend running Mobil 1 or any other group IV oil, made from a polyalkylolefin or PAO base.
However, after running the cleaning cycle with Auto-Rx installed into a group III synthetic and run for 2500-3000 miles, followed by a rinse oil change interval with a group III oil, you can go back to the Mobil 1. The maintenance dose works quite well in group IV oils such as Mobil 1., to maintain cleanliness. Even running the maintenance dose with M1, I would keep your oil change intervals to less than 5000 miles, especially with the modifications.
