What is the difference between fully synthetic and semi-synthetic engine oil?

[OAdrian]

The differences between fully synthetic and semi-synthetic engine oils are: 1. Different base oils: Fully synthetic oil is a mixture of Group III, IV, and V base oils; semi-synthetic oil uses Group III base oil. 2. Different replacement intervals: Fully synthetic oil should be replaced once a year or every 10,000 kilometers during use; semi-synthetic oil should be replaced every six months or every 7,500 kilometers during use. Engine oil, also known as engine lubricant, serves the following functions: 1. Cooling and temperature reduction; 2. Sealing and leak prevention; 3. Cleaning and purification; 4. Shock absorption and buffering; 5. Lubrication to reduce wear; 6. Rust and corrosion prevention; 7. Component protection.