Is it okay to mix oils?

In general, yes. There are a few exceptions, Castor and plant based (as used in some biodegradable oils) are not safe to mix with conventional oils. Other than those few exceptions, mixing oil brands, types (synthetic, semi-synthetic and mineral) and viscosities is fine. The only problem with mixing oils is that the quality of the better oil is diluted by the lesser one.

Updated on: 07/01/2019