I was reading the Motor Oil Bible and in the oil ranking section the Chevron Supreme 100% synthetic 10w30 grade was very highly rated. Can anyone comment on this oil good or bad. Is it a group III or group IV base? I'm thinking of switching to the Chevron. It is a $1.00 cheaper per quart and seems to be better rated (at least by the authors interpretation). I have four vehicles so if I can save some $$ and get a better oil it sounds like a win win. I did a search but didn't come up with much on the full synthetic version of the Chevron oils. Thanks for your input.