[Focus man. Focus.]

Just looking at an oil won't tell you if it is still up to par Mike. I never recomend going that far over a manufactures oil change interval while working @ Castrol. Sure some new car's oil doesn't need to be changed for 40,000K but they were meant for service intervals like that, namely VW and Audi. But they have their own special oil made for them by Castrol that isn't available to the general population in any store. You need to buy it from a dealership. Also the factory filters are strongly encouraged aswell.

If you read the fine print on the bottles of any extended drain oil it tells you that you should ALWAYS follow the recomended factory oil change service recomendations while under warranty. Otherwise you MAY have warranty issues should something major happen. Thats my .02