What is the difference between 20W-40 and 10W-40?

[OWalker]

20W-40 provides better engine protection during cold starts. 10W40 flows more easily than 20W40 at low temperatures. Meaning: "W" stands for winter, and the smaller the number before it, the better the oil's low-temperature fluidity, indicating a lower usable environmental temperature and better engine protection during cold starts. The number after "W" is an indicator of the oil's high-temperature resistance, with a larger value indicating better protection at high temperatures. Gasoline viscosity: Higher viscosity oils also have relatively higher resistance to the movement system, not only consuming power and increasing fuel consumption but also raising oil temperature, making it prone to oxidation and affecting cold start protection.