got a 2nd 99 grand prix w/3.8 motor. checked oil last month. looked ok on dipstick. changed it today. and the amount that came out seems less than expected. i would swear it is 3.5 qts. do not know what oil was in car. put in 10-30 which it is spec'd for. will monitor consumption. car has 110k miles. runs great. no smoke. my caddy takes 7.5 qts. when i drain it, i can hardly lift oil pan. big difference.