What is the difference between full synthetic oil and semi-synthetic oil?
2 Answers
The differences between full synthetic oil and semi-synthetic oil: 1. Different base oils: Full synthetic oil is composed of a mixture of the third, fourth, and fifth types of base oils; semi-synthetic oil uses the third type of base oil. 2. Different replacement cycles: Full synthetic oil should be replaced once a year or every 10,000 kilometers; semi-synthetic oil should be replaced every six months or every 7,500 kilometers. Engine oil consists of two parts: base oil and additives. The base oil is the main component of lubricating oil, determining its basic properties. Additives can compensate for and improve the shortcomings of the base oil's performance, imparting certain new properties, making them an important part of lubricating oil.
As a long-distance driver who has changed engine oil over twenty times, I've concluded that full synthetic oil has more uniform and stable molecules, with significantly better evaporation resistance at high temperatures. The engine noise is noticeably quieter at highway speeds. Semi-synthetic oil, refined from mineral oil blended with chemical additives, shows slower lubrication in the first few seconds during cold starts. Last winter, I tested this: with full synthetic oil, the engine revved past 2000 RPM immediately at -15°C, while semi-synthetic took five to six seconds to catch up. A crucial reminder: turbocharged vehicles must use full synthetic oil to avoid carbon buildup and sticking. My current car runs exclusively on full synthetic, extending the maintenance interval to 10,000 km—proving more cost-effective than semi-synthetic changes every six months.
