What does the W in engine oil mean?
2 Answers
The letter W in engine oil models stands for winter, which means winter. Below is a detailed introduction to the specific classifications of automotive engine oil: S at the beginning represents gasoline engine oil: Specifications include SA, SB, SC, SD, SE, SF, SG, SH, SJ, SL. C at the beginning represents diesel engine oil: Specifications include CA, CB, CC, CD, CE, CF, CF-2, CF-4, CG-4, CH-4, CI-4. From SA to SL: With each additional letter, the performance of the engine oil improves compared to the previous one, containing more additives to protect the engine. The more letters there are, the higher the quality grade. The oil grades of international brands are generally above SF level.
I've been running an auto repair shop for over a decade, dealing with engine oil every day. The 'W' actually stands for 'Winter' in English, and the full specification should be in the format of XXW-XX. For example, in a grade like 5W-30, the '5W' at the front indicates low-temperature fluidity - the smaller the number, the easier it is to start the engine in cold weather. The '30' at the back refers to high-temperature viscosity - the larger the number, the better the protection, just like how we prefer thicker porridge in winter to keep us full. When choosing engine oil, you shouldn't just look at the 'W' rating; you need to check your vehicle's maintenance manual. Nowadays, more and more new cars use oils starting with 0W, thanks to advancements in full-synthetic oil technology that provide better engine protection.
