I have a question about the ATF filling procedure for a GM 5L40E (A5S390R) transmission.
The instructions require the engine to be running, selecting each gear position, return to "Park" & the ATF to be at least 80 Deg F before checking the ATF level is at the fill hole.
My question is does the transmission have to be level to do this ? (i can hold a bubble level to the ring of bolts on the sump pan). If the vehicle is parked on level groung the transmission is NOT level because it is slung under the car at a slight angle.
Tranny level or vehicle level ?
Also what is the average life expectancy in miles for a GM 5L40E (A5S390R) ?