well napa should be correct. if i'm correct all oil filters vary in sizes and as long as it fits and does the job you should not worry. my car takes 4 quarts--i have the obs 2.2 model--but i always buy 5 just to make sure. you have to fill up your engine with 4 quarts at first, let it run at idle for awhile, then check your oil level. i always drive the car somewhere and check it about 15 after i get home just to be sure.