Transmission Fluid Change

**makthenif** · 08-23-2009, 02:52 PM

Does anyone have tips for the trans fluid change? I have done this before on other vehicles...but not on my '96 sub...always had someone else do it. Thanks

**unplugged** · 08-26-2009, 08:51 PM

I had mine done at the shop, but it can be a DIY project too.

Some folks pull the return line and attach a clear hose that dumps into a container. Start the engine and pour fresh fluid in the filler tube to match what is coming out to the dump container. Use a clear container and mark 1 quart levels so that you can put back what is coming out. Be sure to check the fluid level once you've flushed the old fluid out and remember it's always easier to add a quart that take one out.

Note this method doesn't completely flush the old fluid out. It's more of a dilute it til it looks new.

Good description of the various methods here: http://www.gadgetonline.com/TransFlush.htm

**jbeall** · 08-26-2009, 09:06 PM

Amsoil has a step-by-step set of instructions on how to do it the way unplugged described:
https://www.amsoil.com/faqs/ATF_and_...Procedures.pdf

I'm thinking about doing this method shortly on my 2003 Yukon XL. I have to figure out where the transmission fluid return line is, though.

You mentioned that you've changed transmission fluid in the past--how have you done it before?

-Josh

**Jimmiee** · 08-26-2009, 09:52 PM

Originally Posted by jbeall

Amsoil has a step-by-step set of instructions on how to do it the way unplugged described:
https://www.amsoil.com/faqs/ATF_and_...Procedures.pdf

I'm thinking about doing this method shortly on my 2003 Yukon XL. I have to figure out where the transmission fluid return line is, though.

You mentioned that you've changed transmission fluid in the past--how have you done it before?

-Josh

Usually the hot oil enters the bottom fitting and returns to the transmission via the top fitting providing nobody's messed with the lines.

**makthenif** · 08-30-2009, 10:23 AM

Well, I made sure the truck was on a flat level, removed the pan, and filter, let all the fluid drain. Cleaned the pan and old gasket material, also cleaned the magnet, removed the old filter, installed the new filter, replaced the pan with new gasket and gasket seal. Now this is a fluid change not a flush. I didn't mess with the torque converter. Finally refilled.

**IrishBrewer** · 09-04-2009, 08:21 AM

Originally Posted by jbeall

Amsoil has a step-by-step set of instructions on how to do it the way unplugged described:
https://www.amsoil.com/faqs/ATF_and_...Procedures.pdf

I'm thinking about doing this method shortly on my 2003 Yukon XL. I have to figure out where the transmission fluid return line is, though.

You mentioned that you've changed transmission fluid in the past--how have you done it before?

-Josh

I have an '02 and I use a similar procedure. There are two tranny lines going in/out of the passenger side of the radiator. The one on the bottom is where the fluid is pumped out of the tranny and into the radiator. This is the one you want to remove to attach some clear tubing. The lines are held in with a wire-type clip - be careful not to lose these as they aren't easy to find. To re-attach these lines, the wire clip goes on first and the line just snaps in.

One other thing to keep in mind is that the pan is difficult to remove completely due to interference from a shift bracket and an exhaust crossover pipe. Next time I do this job, I'll be removing the crossover pipe.

Lastly, this is definitely a two person job because the fluid is pumped out very quickly. You need to have all of your quarts of fluid at the ready to be poured in and you need someone ready to shut off the engine as soon as the right amount of fluid has been pumped out.

**makthenif** · 09-04-2009, 06:38 PM

does anyone know where the tranny model number is located on the truck?

**jbeall** · 09-04-2009, 07:46 PM

Originally Posted by makthenif

does anyone know where the tranny model number is located on the truck?

You're asking whether you have the 4L60E or 4L80E transmission, right?

I was told that the 1500 (1/2 ton) models have the 4L60E, and the 2500 (3/4 ton) models have the 4L80E.

Can anyone here confirm that this is the case?

-Josh

**makthenif** · 09-05-2009, 10:48 AM

yes. exactly.

**SkiBurban** · 09-05-2009, 11:58 PM

My rig has a drain plug on the bottom of the transmission, which will only drain out whats in the pan, and not in the torque converter. I really like the idea of just removing the lower hose, and refilling back into the dip stick tube.
Anyone toy with the idea of cutting the line and splicing in 2 valves and a hose, to facilitate the next time I have to do this?
I was always told the 4L60E is a fine transmission, as long as you change the oil on a regular basis, and no more than 20K miles when towing alot.

Thanks
Paul