So what is the best oil out there for v-8's? I have about 7 or 8K on my new 406 and it's time to drain out the cheap "break in" oil for the last time and pour in some good stuff. I was thinking Mobile 1 synthetic 15-50. I have heard royal purple is a very good oil too. What do you guys use and suggest, I wan't only the best for this motor because it gets used and abused and engine longevity is important. Is it really true that a good synthetic helps the motor rev up just a little faster and help it gain just a couple of extra horsepower?