| I don't think it makes much difference. I had always heard that the smaller the spead in viscosity, the more thermaly stable the oil. Living in southern California means that I don't worry too much about cold weather operation, so I use 10-30. My 94 went about 230,000 miles without any major engine problems, and the commpression was well within spec when I did the last tune-up at something less than 200,000 miles. It passed California emissions at the time of sale, so the engine had to be in fairly reasonable shape. And that was using whatever name brand oil was on sale at the time, no synthetics, and changing the oil generaly at 50 - 20% oil life remaining. And for the entire time that I had it, it used about 1 quart every 1500 miles. It had slight leakage around the middle, and the bottom pan but no drips. A weep might be a better description. So far at 108,000 miles our 97 is about the same, it might use a slight amout more oil. It developed a drip at about 50,000 miles and it was repaired under warranty. | 
