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

[Muhammad]

Synthetic oil and semi-synthetic oil differ in the following aspects: 1. Base oil composition: Synthetic oil is formulated by blending the third, fourth, and fifth types of base oils, while semi-synthetic oil uses only the third type of base oil. 2. Replacement intervals: Fully synthetic oil should be replaced annually or every 10,000 kilometers, whereas semi-synthetic oil requires replacement every six months or 7,500 kilometers. The functions of engine oil include: 1. Lubrication to reduce wear; 2. Cooling to lower temperature; 3. Shock absorption and cushioning. Precautions for oil changes: 1. Drain the oil when the engine is warm for better fluidity; 2. Ensure the oil level reaches the dipstick mark during refilling; 3. Select the appropriate oil grade based on driving conditions, frequency, and the specific requirements of the vehicle's engine.