Ok guys, I ain't never had an auto before now. When I bought the truck, it had a recently rebuilt 727 in it. The fluid probably needs to be changed as I've put quite a few miles on it. Do you just drain the fluid outta the pan or is there more to it, torque converter etc. I want to keep this thing goin as long as I can. Do ya'll think I should run synthetic fluid in it? Any advice would be appreciated. Thanks

 

To do it right (or, quasi-pseudo-right) you drop the pan, empty out the old fluid there, and change the filter on the valve body. Then you reinstall the pan, fill it full of clean fluid, and pull the return line off of the last transmission cooler. Turn on the truck and dump new ATF in through the dipstick hole as it pumps the old ATF out of the disconnected line. When you start getting the new ATF out through the line, you've got most of the old stuff out.

That might not be the fancy "correct" way of doing it, but lots of old salts do it that way. Seems good to me as long as you don't run it out of fluid...

They typically say to not run synthetic fluid in an old transmission. It's supposed to be good for higher temperatures, but also expensive.

 

I might try that, IDK, ain't never had an auto before. Manuals are so easy, pull the plug, drain, reinstall, pull top plug, refill, reinstall, ride.

 

100% agree with begle. unless you have a tranny flush machine that's about the best way to do it.

 

I heard of people just dropping the pan and filling, but you only get about 50% out. Then they do it a couple more times fairly soon so they pretty much have fresh throughout, but not very efficient. Flushing is the way to go.
Any yes, synethetic is a good option. Run cooler and last longer

 

I'm assuming you gonna recommend Amsoil. Thanks for the input.

 

I do alot of transmission services here. All with Amsoil (Duh! ).

Here's what we do -

Drop the pan and then filter.

Crack the 10 VB bolts loose. Don't remove the VB, just loosen it so the fluid trapped in the case drains.

Pull Both Cooler lines. The rear most line is the return. Cut a 2-3 foot long length of garden hose. It will slide over the cooler line snugly and not blow off. Inert other end in a bucket or drain pan.

The Front cooler line will drip, so be ready for that. Now, using clean, dry compressed air and a blowgun with a rubber snubber tip on it, seal the snubber against the forward tube. GENTLY apply air pressure slowly, it will blow out the majority of the fluid. The more fluid you pump out, the more air you can apply.

From our experiences, this usually gets about 80-90% of the fluid out. We can tell this by how much goes back in the system when we refill it.

Just don't let the transmission run dry. Bad news there.