the first number is the starting weight---meaning when you start your car that is the thickness of the oil. The second is the runing weight how thick the oil is after the motor heats up. your cars book should tell you at what OUTSIDE temp to run what oilOriginally posted by Martin Can u please tell me what is the different between the engine oil like 10W40 , 10W50, 20W50.......etc. I just wan to know what is these number means.......... thank you.
Yipee