So far you've all missed the target so to speak about the viscosity ratings on Multi-weight Oils. Some are closer than others.
Years ago you had single weight oils, SAE 10, SAE 20, SAE 30...(you get the idea). The higher number the thicker the oil. Lower # for thinner oil. Thinner oils for winter & thicker (higher#)for summer. Along came the Multi-Weight oils, 10w-30, 20w-50, 5w-30 etc. The 1st # represents the oils viscosity characteristics in cold temp. It is a comparative #. So in other words a 10w-30 oil will flow like straight weight SAE 10 in cold weather. The 2nd # represents the oil's viscosity at higher temperatures. So again it's a comparative #. The same 10w-30 oil would flow like a straight weight SAE 30 at higher temperatures. 20w-50 flows like an SAE 20 in cold & an SAE 50 in warm temp.
It's like having 2 different grades available in your crankcase at the same time. Or you can think of it as bipolar if you like!
And the "W" does stand for WINTER.
The tests are done at specific temperatures for the higher # and the lower #. It doesn't directly mean weather the engine is warmed up or not.
So if you took 3 separate bottles of motor oil, SAE 10, SAE 10w-30 & SAE 30 and ran them all individually through a viscosity meter at the same temperature(say room temp) you'd get 3 different viscosity readings.
Have I confused the s**t outta everybody yet?
