Originally Posted by samclem
I think we might already be there with motor oil. Our new car (Honda CR-V) specifies use of 0W-20 oil.
I completely agree. I was an auto mechanic for 8 years...and I own an older CRV now. Even if I bought a new one, there's no way I'd use 0W-20...particularly in the summer. I'd have to do some research...but typically I use one weight heavier than they recommend...or in your case that would be 10W-30.
For those of you unfamilar with oil grades... the first number is how "viscous" the oil is at a particular temperature (don't know the exact temp...but think of it as the thickness in winter)...and the lower the number, the thinner the oil. The W stands for "Winter", so a 0W-20 has the "viscosity" of a 0-weight oil in winter, and a 20-weight (thicker) oil in summer.
If you were to open up a 0W-20 and a 20W-50 oil, the 20W-50 would be NOTABLY more viscous (thicker).
If you open a 0W-20 oil in winter and videotape yourself pouring it, then heat the oil up to a summer temperature and pour it again, it would be notably thinner at the warmer temperature.