switching oil

[PKRWUD]

Mobil 1 does not have a conventional oil base, it is pure synthetic. There are minute traces of mineral oil that is used as a carrier for the additives, but the oil itself is synthetic. As far as mixing the two, their website says:

Mobil 1 is compatible with conventional motor oil, should it be necessary to mix the two. The additive package in Mobil 1 has been specifically developed to work with its synthetic base fluids, so diluting Mobil 1 with conventional oil will reduce the superior performance characteristics of Mobil 1. While mixing conventional oil and Mobil 1 is acceptable, we do not recommend mixing different types of synthetic oils, since they may be composed of different synthetic base fluids. Change the oil and filter before changing from another synthetic oil to Mobil 1.

Switching back to conventional oil will please your wallet more than it will please your engine, but as long as you change it and the filter regularly, you will probably be okay.

Take care,
-Chris