I have a question. Those of you who are running 20K oil change intervals on quality synthetic, are you putting on that many miles in a year or does it take longer?
Never used the Amsoil but have noticed products like Mobil 1 "Extended Performance" and "Annual Protection" advertise that they are good for 15 or 25K miles or up to one year. What if you only drive 6 or 7k a year on a vehicle? Technically, you are supposed to dump it but I don't really see why, especially if you get the vehicle out on the road occasionally and get everything heated up.
I know the only real way to answer this is to have a lab analyze the oil but just wondering if anyone had any opinions.
Your last sentence hit the nail on the head, the only true way of knowing is through UOAs (Used Oil Analysis)
I can see the additives in oil performing to a certain mileage threshold, but have never understood the "or up to one year" statement. Oil doesn't use a calendar, so perhaps certain chemicals in the ad pack deteriorate with time.
