My car has over 150K and started shifting rough on the lower gears. This mainly happens during stop and go traffic. Been reading all sorts of posts about the transmission in this car and opted to try to do a drain and fill. Brought the car to a reputable shop and in the end, got charge for 4 quarts of WS ATF. I asked how does the car take that much oil and he said dropping the pan was the reason.

Now I'm very confused. I thought dropping the pan yielded at most 1.5 quarts. My 2 thoughts are:

1. He just overcharged me (that's crappy, but at least the car is not overfilled).
2. The car is overfilled. Can you overfill a transmission by more than 2.5 quarts?

Can anyone help me. I read somewhere that maybe they used a pressure machine to push the oil into the transmission, and in that case, more oil will be used, but still not 4 quarts.

 

most modern transmissions cannot be drained that way. you only get 1/3 of it out. conventional wisdom is to do it 3 times in a row, driving it a few miles in between to get most of it replaced. usually takes a lot more fluid. how did the old fluid look, what color was it and did it smell burnt at all?

 

Usually they do it multiple times to get all the old oil especially at 150K miles.
Otherwise they can use a suction device to get all the oil out but at 4 Qts that seems a lot for that. You can't really overfill a transmission because if you do it will just come out of the drain hole while you pump/pour into the inlet hole.

 

I didn't see the fluid at all but told it was kind of yellow. I was asked to go back after driving about 8000 miles to do another change.

 

The transmission fluid should be red when its new, and turns black when its old... yellow means he most likely lied and didn't even change your fluid. If a flush was performed, the transmissions could use up to 15 quarts of WS ATF. As far as doing a drain and fill, the transmission fluid has to be a certain temperature before it can be properly checked. If the temperature is over or under, you'll get an incorrect level.