I've been using the 5qt walmart jugs of Mobil 1 5w30 (are these any worse than the regular) for $25, and I am always missing literally quarts of oil everytime i change the oil. I change it appx. every 3-5k miles, and do mostly city driving with a fair amount of agressive engine revving. I figured it was just my engine, but I have been reading alot of things about people blaming M1's quality for the burnoff. i have a 2000 firebird 3.8L with 140k miles, the motor itself is still running good. I want to give it a better oil if m1 is as bad as everyone is saying. I thought about GC 0w30 but cant find it anymore. ive heard alot about Penz plat. as well. if royal purple or redline or amsoil are far superior i wouldn't mind the extra price. what would you guys recommend for me?