Funny, i read in an article that multigrade is always better than monograde simply because of its ability to maintain constant viscosity in wide temperature levels. The numbers in multigrades (ex. 15w-40) correspond to measurement of liquid viscosity (viscosity naman is measure of how fast a fluid pases thru a standard tube/pipe) which corresponds to the lowest engine temp and highest engine temp. IN effect the multigrade will not exceed a deviation of 25pt. viscosity from cold start to fully warm engine. That's why the article said multigrades are better....at least thats what it said....that's also why multigrades are more expensive than monogrades.