i too will be giving the amsoil eao filter a shot shortly. i plan on using the HDD 5w30 and the oversized filter for my neon with a 15000 mile interval. i could probably get away with going 20000 to 25000 because i am on the highway a lot. but i like to have a cushion. i will do a used oil analysis between 7500 and 10000 just to make sure ill be good for the full 15000. if i am then i will continue on to 15000 and may do a used oil analysis when i drain.