Is Castrol SM a Synthetic Engine Oil?
2 Answers
Castrol SM is a synthetic engine oil. SM Position: SM is one of the engine oil quality grades, ranking third, just below SN and SP levels. Notes on Selecting Engine Oil: In addition to the viscosity grade, the quality grade is also an important indicator. Generally, the level recommended in the maintenance manual or for the engine model is sufficient. However, if you frequently drive in congested traffic conditions, it is recommended to use a higher-grade engine oil, which is more environmentally friendly and economical. Nevertheless, car owners do not necessarily need to pursue the highest-grade oil. While its oil quality and performance may be relatively superior, its price will also increase accordingly.
I previously used Castrol engine oil and specifically researched its product classifications. Castrol SM does not specifically refer to a synthetic oil model; SM is actually the API (American Petroleum Institute) oil quality grade standard, which was the mainstream specification around 2010. Castrol offers both mineral and synthetic oils, both of which can be labeled as SM grade. For example, the Edge series is fully synthetic oil, Magnetec is semi-synthetic, and GTX is the mineral oil series. All of these can meet the SM specification, but you should check the label on the bottle for specifics. Fully synthetic oil performs significantly better in terms of low-temperature fluidity and high-temperature protection, especially during cold starts in winter. For maintenance, it's most reliable to directly check the 'Fully Synthetic' or 'Synthetic' label on the packaging.
