How to Distinguish Between Synthetic and Semi-Synthetic Engine Oil?
3 Answers
Distinguishing between synthetic and semi-synthetic engine oil mainly involves the following aspects: 1. Semi-synthetic oil is a product based on mineral oil, refined through hydrogenation. Synthetic engine oil is derived from ethylene and propylene dispersed from natural gas in crude oil or natural gas, refined into high molecular lubricants through complex chemical reactions such as polymerization and catalysis. 2. For the same oil film requirements, synthetic oil has lower viscosity, while semi-synthetic oil has higher viscosity compared to synthetic oil. 3. Semi-synthetic oil is mainly used for economical vehicles, while full synthetic oil is primarily used for luxury vehicles. 4. The amount of additives differs, with more in full synthetic oil and less in semi-synthetic oil.
I'm really into studying car maintenance knowledge. The key to distinguishing between synthetic and semi-synthetic oils lies in the packaging labels. Full synthetic oil will always be marked with 'Full Synthetic' or '100% Synthetic,' and the bottle may also indicate PAO or ester-based oil. Semi-synthetic oils usually have terms like 'Synthetic Blend' or 'Semi-Synthetic.' The quality of the base oil is also an important criterion – full synthetics use Group III or higher base oils, offering excellent low-temperature fluidity. Price-wise, full synthetics are about 30% more expensive, but their oil change interval can reach 10,000 kilometers, whereas semi-synthetics need to be changed at around 7,500 kilometers. If you come across oil with unclear labeling, you can directly check the technical specifications on the brand's official website.
Last time I changed the engine oil, I specifically consulted an experienced mechanic about this issue. The simplest way is to check if the bottle has the words 'fully synthetic' printed on it - reputable brands always mark this very clearly. There's also a difference in smell: synthetic oil has a relatively mild odor, while mineral oil has a heavier petroleum smell. Color can also help with identification - fully synthetic oil appears more transparent and clear, and the color change in used oil is slower too. Additionally, synthetic oil feels smoother when poured, with semi-synthetic oil's fluidity being somewhere between mineral and synthetic oils. It's best to keep an eye on the oil change process to prevent workshops from adding semi-synthetic oil while claiming it's fully synthetic.
