So, I went and ordered a few early Xmas presents for myself recently. Picked up a case (12 qts) of Royal Purple Motor Oil, some K&N oil filters, and a K&N drop in air filter. Changed all on Sat. Dunno if it's just mental or not, but she appears to be running smoother than before. Change was done at 3,200 miles, filter and oil. I've never used RP before but always heard good things about it, figured I'd give it a shot after seeing the prices for Mobile1. Paid $86 for the case with free super saver shipping from Amazon. That'll be good for 2 oil changes. So far I'm impressed, now let's see if mileage changes any.
I would be VERY interested in these findings as well. I have a friend of mine that recently built a motor for his '71 Mach I and he said just by using RP instead of other oils it gave him a 5HP increase....He's not really going for MPG in his car