guys if you can chime in and tell me if im right here.

1) Drop the pan put new filter in and close it up and add 3 quarts.
2) I think the return goes to the top of the radiator and supply to tranny goes out from the bottom. So in that case disconnect the supply line going out to the radiator and get a tube. One tube goes out from the radiator to to a 5 gallon bucket, and other tube attaches to the line feeding into the tranny and that tube would be in a 5 gallon bucket filled with fresh oil.
3) start the truck up and leave it in park and watch the empty bucket fill up and at the same time the bucket with clean fluid will get sucked into the tranny.
4 Once the bucket fills up and you see clean fluid come out the tranny it should be flushed which will take im guessing 15-20 quarts to be safe you can turn the truck off.


So am i wrong here guys?? Or will i have to manually fill because ive done this before and i just want to be sure 4l60e will suck the fluid in and then push it thru the radiator out the exit side so i can clean everything in the entire system even old fluid in the radiator. Prob going to use amsoil or mobil 1. Truck has 45K miles.

 

There are several shops that use a similar method of changing the trans fluid. I have that done about every 30k because of the heavy towing I do. They change the filter every other change.

 

If you have the deeper GM pan, you will need to add at least 4qts after you bolt it back up. That 3qt figure is for a regular 4L60E pan.

 

Does my 07 Sierra Denali Classic have a normal or deep GM trans pan?