1. Semi-synthetic
After the semi-synthetic oils is a mineral oil-yl group cleaved coupled to synthesize, can be obtained with the more uniform chemical composition, color and similar mineral oil based as a clear pale microstrip amber, refining costs so high the price of expensive, but good oxidation resistance, is a very good long-acting oil service life of about twelve months.
Now people are semi-synthetic oils and the economical performance can be oil type of people.