If I wasn't clear, I wasn't stating Regular vs Synthetic oil, I'm going to continue to use synthetic in the new car even if I'm not certain of the benefit. My real question is what brand. Some of the stocks info was good.

Extended operation above 90deg and below 0 degF--especially starting it once or twice a day--qualifies for the alternate maintenance info. My manual is in the car, but I'm pretty certain those were the temp breakdowns; I know the 90degF is right. (Rear differential actually goes to 140wt if you're constantly above 50degF and running above 90degF)

If you tow a load of spare parts from Phoenix in the summer up to BigSwede and stay the winter, I'd change all the fluids before the first frost. <img src="/forums/images/graemlins/smile.gif" alt="" />