I normally do the 3 months or 3000 miles (including filter)it is relativly cheap and my cars have never needed rings or valves( the maxima is upt to 117,000 miles and drives like new) I have heard that acura is insistent on not changing the oil to the full recomended darin interval of around 7000 miles any body got any insight into this? I'll probably go ahead and dot he 3 and 3000 anyway cause I can't see how it can hurt. DZ