SAE 15w-40 has been the dominant viscosity grade in the past few decades. Its use has peaked and is now forecast to decrease by 30% by 2029, with SAE 10w-30 growing to about 40% of the US market ...

Based on what we've just learned about engine oil codes, a 5W-30 oil has a viscosity grade of 5 at low temperatures. ... When it comes to engine oil, the SAE maintains a set of oil viscosity ...