Motor Oil Info

The first one is viscosity basically. 0w is some thin stuff. If you were to put in to a comparrison, 0w would be like water and 20w would be like syrup. The second number is almost like a temperature rating. a formula such as 10w-20 would be better suited for cold weather and 10w-40 would be better suited for warmer weather. 30 is the weight that most people use because it is a good typical balance for all season.

*someone tell me if I have the weights backwards or not...........

5w-30 indicates a 5 weight oil that performs like 30 weight when it's hot. Whereas 5 weight oil would perform just like you'd expect 5 weight to perform when it's hot. Metal expands when it heats up and requires better lubrication when hot. That's the reason for multiweight motor oil.


Edit: Here's a better description

http://auto.howstuffworks.com/question164.htm

the number before the w is the weight of the oil when cold, 0C i believe. the "w" stands for winter. the second number is the weight of the oil at operating temperature. a 5w30 would be thinner when cold than a 10w30. however different oil manufactures 30 weight are slightly different. a lot of newer cars are supposed to run a 5w20 or a 5w30. the 4.6 motor for example wants 5w20 in applications in the US, however they use 20w50 in applications in Australia, and there are no differences in the motors.