alright, well ive got like 700 miles on my oil since i changed it last. i went with 2.5 qts of delo 400 and 2.5 qts of M1 10w30. i had to add a quart of oil last week and the only thing i had was the delo. im just wondering if its necessary to change the oil since there is still some M1 in there before i do auto rx or is there not enough for it to really make a difference. also, do you think i really need to change the filter or will i be alright until the rinse cycle. its a 5.0 mustang with 204k miles on it. i just dont know how much longer i can wait to put this stuff in the motor