Choosing the Best Oil while Motor Cleaning With Auto-Rx Simple, conventional, mineral oil, sometimes called dino oil, works best for the cleaning phase and rinse phase of an Auto-Rx motor cleansing. With conventional motor oil there are no polar ingredients attracting oil to metal surfaces. This is important in facilitating the released of dissolved contaminants to be carried away by the host motor oil. With a recommended 2,500 mile run for cleaning with Auto-Rx installed, and an important 3,000 mile rinse phase, running conventional oil for these relatively short oil change intervals, will also save you money. Whenever possible, this recommendation will maximize the effectiveness of your Auto-Rx cleaning application. The engine protection offered by conventional oil over a 3,000 mile oil change interval is equal to a more costly full synthetic. Motors that are specified for synthetic only, are due to a corresponding long drain interval. By long drain interval, we mean 5,000 to 10,000 miles. For those that can not find the proper spec conventional motor oil, we suggest running a group III synthetic oil, which is merely ultra refined conventional oil. The use of a conventional mineral oil is essential in addressing seal leak issues. Once your motor has been cleaned and rinsed the Auto-Rx maintenance dose works extremely well with any motor oil of your choice. In conventional oils, additional cleansing will occur, as well as providing supplemental lubricity, as well as neutralizing acidic formations. In synthetics, the maintenance dose supports a healthy TBN(total base number) and has shown to reduce wear metals.