What is the concept of SL-grade engine oil?
2 Answers
SL-grade engine oil is considered a lower-tier classification among commonly used quality grades of engine oil. The functions of SL-grade engine oil are as follows: Anti-friction: When the engine is running, the oil forms a thin film on the surfaces of various components inside the engine, preventing direct contact and friction between these parts. Cleaning: This refers to the removal of carbon deposits, oil stains, and other contaminants generated during combustion, either by dissolving them in the oil or filtering them out using an oil filter. Engine oil cleans the engine and removes residual impurities from the filter, protecting metal surfaces from corrosion caused by acids formed during combustion. Additionally, engine oil carries away combustion residues (carbon deposits), combustion by-products of the lubricant, or oxidation products (low-temperature sludge), quickly settling them to the bottom of the oil pan.
I've been running an auto repair shop for over a decade. SL-grade oil is a gasoline engine oil specification from the API standard introduced in 2001. It improved oxidation resistance and dispersancy compared to the previous SJ grade, better preventing sludge formation. It was quite advanced back then, but is somewhat outdated for modern vehicles. Most cars on the road today are better suited for SN or SP grades, especially turbocharged models. However, SL is perfectly fine for older vehicles like pre-2005 models - my shop still stocks several SL oils for regular customers, as it provides adequate protection for carbureted engines. The key is following your manual's requirements rather than blindly chasing newer specs.
