Last 5 tankfulls = 38.4MPG on the old Saturn. It's rated at 35MPG. Some city driving, lots of highway at 70+MPH. M1 5w-30SM in the crankase. BP/Amoco 93 octane shows a full 2MPG difference. Even 1 tank that tickled 40MPG! I've kept fuel records for the past 18months. Not bad for a car with 150K. X This isn't a thread with great insight to oil. Sorry. Just a happy FP and LC customer.