I'm also confused in oil grade,
if an oil is 20w-50 what does its meaning actually
i did some googling and found that there are two types of oil grade first is single grade and second is multi grade, and 20w-50 means it is multigrade oil and 20w is its viscosity on normal temperature where w stands for winter, while 50 is on temperature of 100'c, but I'm again confused, how it is possible for an oil to thin on normal temperature(20w) and become thick on higher temperature(50)
then in a Wikipedia articles i read That it is not viscosity, not 20w and neither 50, it is actually sae grade, while sae grade shows viscosity
fully confused