I have a 7 quart pan and i run around 6 quarts in and do gain a little hp over 7 quarts but will not go lower as at 5 1/2 quarts at the end of the 1/4 mile when i slow down my oil pressure will drop to 20 psi and to me that is not good...so that is why i run at least 6 quarts and at the end of the 1/4 my oil pressure is still up at normal pressure when i slow down..