Just bought an 03, Ford F250 Super duty, V10 motor. I have about 300 miles on it now, I think the break in is 500 if I am not mistaken. With this truck, I would like to stay with the same oil all the time. It does kind of scare me though, the manual calls for 5W20. That is almost water I think. I will use it, I assume the people that built it know what's best. So, for something so thin, is synthetic the ONLY way to go, or would a good dino, like Chevron Supreme be just as good, considering cost? Any help appreciated. Also, what do you think, 500 miles for the first change, or 1000? Thanks!!!