Anda mungkin perasan ada perkataan "API SN" atau "API SM" pada botol minyak. Ia TIDAK BERKAITAN DENGAN KUALITI MINYAK tersebut, sebaliknya ia merupakan gred servis (service grade) sesuatu minyak enjin. Gred servis di sini bukan bermaksud berapa lamakan sesuatu minyak boleh tahan sebelum perlu diservis.

These letters, such as API SN and so forth denote the oil's service grade. It does NOT denote the quality of the oil.

Continuing our series on engine oil basics, let us look at the differences between mineral, semi-synthetic and fully synthetic oils.