oil weight

I love howstuffworks.com! :)

Tony

I stopped going to howstuffworks a long time ago. I started to look up=20 things I already knew about just to check how good they are and they=20 were way off on a lot of things. =20 First off let me say... Does a quart of 20w50 weigh more than a quart of=20

10w30? does the 50 mean that it weighs 40% more than the 30? No... So=20 where do people get "weight" from? How much a quart of oil weighs has=20 nothing to do with its viscosity. Those numbers have to do with the oils=20 viscosity at a given temperature. W was added to multi-grade oils=20 indicating it was designed to have a certain flow in "winter"=20 temperatures.=20

"""Viscosity measurements designate thickness and thinness.=20 To tell you how thick or thin an oil is, the Society of Automotive=20 Engineers (SAE) has established a viscosity classification that appears=20 on the top of oil cans. The numbers you'll see go from 5W, which would=20 be for very thin oil used in extremely cold weather conditions, up to a=20

50, which would be for very thick oils that have special uses such as=20 very hot applications or racing engines. These numbers designate the SAE=20 Viscosity Grade.

You'll see SAE Grade numbers with "W" after the number; such as SAE 10W.=20 These are classified by a viscosity measurement at low temperature.=20 Thus, the "W" classifications give an indication of how low the outdoor=20 temperature can get and still have the oil provide good starting and=20 good fluidity for low temperature lubrication. The lower the number, the=20 thinner the oil - which is needed at low temperature. Five "W" SAE=20 Grades are specified by SAE, these being 5W, 10W, 15W, 20W and 25W.

The "non-W" SAE Grades are classified by a viscosity measured at 100=B0C=20 (210=B0F). This is done to tell the user how thick or thin the oil will be= =20 at engine operating temperatures. There are 5 "non-W" SAE Grades 20, 30,=20

40, 50 and 60. Again, the smallest numbers are the thinnest in=20 viscosity.

A can of oil may have only one SAE Grade listed on the label. These are=20 called single graded oils. For years this was all that was available.=20 The car operator in the North would change to low viscosity such as 10W=20 oil in the winter, and then to a higher viscosity such as 30 for summer=20 driving.

Today, more frequently the car owner finds one "W" Grade and one "non- W" Grade on the label such as SAE 10W-30 or 10W-40. These are called=20 multi-graded or multi-vis oils. Oils so labeled will have the low=20 temperature starting ability of the lowest "W" Grade on the label and=20 will still protect the engine after it warms up with oil having the=20 thickness of the "Non-W" Grade."""