What is the concept of SL-grade engine oil?

[VanEllie]

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.

[VonLeah]

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 It was quite advanced back then, but is somewhat outdated for modern vehicles.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.

[VonEmmanuel]

As a car enthusiast, I pay close attention to engine oil specifications. SL is an API-certified oil grade, equivalent to the standards from the early 2000s. Nowadays, SP grade is the mainstream, incorporating many new technologies compared to SL. However, my old Jetta runs perfectly fine with SL oil, especially starting smoothly in winter. SL oil has slightly weaker high-temperature stability, so it's important to monitor oil temperature during summer traffic jams. Using SL oil in a modern new car wouldn't be wise, as it might affect the lifespan of the catalytic converter. In fact, SL oil is quite rare in the market now, and you'd need to search specifically to find it.

[MelanieLee]

The SL grade of engine oil is a specification standard introduced in 2001, offering improved high-temperature detergency and oxidation resistance compared to its predecessors. Simply put, it helps reduce engine carbon buildup. With the upgrading of emission standards, API has since introduced higher-grade oils like SN and SP, which provide better wear protection and fuel efficiency. SL-grade oil is suitable for vehicles manufactured before 2010, as newer car manuals now require higher-grade oils. A mechanic taught me to identify SL oil by the donut symbol on the container—look for the 'SL' marking. Regularly changing your oil is more important than obsessing over the grade.

[VanPaige]

Friends looking to save on car maintenance costs can consider SL engine oil. This type of oil is significantly cheaper than the current SP grade, and it's perfectly suitable for older vehicles. My 2003 Bora has been using SL mineral oil all along, passing annual emission tests without issues. However, three reminders: first, don't use it in new vehicles equipped with particulate filters; second, in high-temperature areas, it's advisable to shorten the oil change interval; third, try to buy from major brands to avoid counterfeit products. When purchasing engine oil, more expensive doesn't necessarily mean better—the key is that it meets the engine's design specifications.