with conventional oil I don't mind changing it every 3k because you can get the stuff for $8 a gallon if you look around for a special. But I'm thinking of buying a new car with this new GM discount, and since this will be the first time I get to maintain a vehicle from the start I was thinking of using synthetic.
Man that stuff is expensive though. I certainly wouldn't leave oil in a gasoline engine for 15k miles, but I was thinking maybe I'd change it every 7500.

I've never seen this "ams" stuff, where do you get it?
Is it good to just replace the filter every 3k and then
add something like Lucas to put the additives back in?