i am in the process of changing the oil and filter in the tranny. I read that the oil pan holds 4 qts of oil and the torque converter holds about 5 qts, so by putting 4qts of new oil in the pan ,that oil is going to mix with the old dirty oil in the TC. also the old oil is original from bmw and the new oil is mercon and they say do not mix oils,what does one do here? fill the pan with new oil and flush it and refill? no idea what to do any help is greatly appreciated in this confusion . thanks in advance for your help guys...: