from what I'm reading there may be some people out there afraid to use synthetic oil. synthetic oil reduces running temps up to 30+ degrees. for LSD like mine I use synthetc oil with LSD additive. I also use something in my radiator called Water Wetter from Red Line. Tests show a 40-60 degree drop in flash temp in the coolant. It also has a friction modifier in it to lube the water pump (post t-belt). I even went as far as to find synthetic ATF for the trans after the overhaul and shift kit treatment and added a tranny cooler (50,000lb) for towing (overkill). I add an oil additive (prolong) to the synthetic oil in the engine every 6,000 mi., and I still change the oil every 3K. As far as engine oil I use Mobil 1 racing oil in the 10W30 variety.