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I often see members asking about fluid changes for the 6l80 transmission. Whether you do it yourself or pay someone else, it's best to know how it's done.
If you take it to someone else, ask them the procedure before you let them touch the car. If they can't give you correct answers, run away quickly. It's way too easy to do it wrong and wrong is bad. However, you might ask for a lower labor rate in exchange for educating them.
If you're doing this yourself and using jackstands, use safe methods to raise the car enough to get under, but not so high that you can't easily reach the transmission. Be aware that at one point you will have to be under the car for a minute or two while the engine is running.
Make sure the car is level. This is important, since if not level, the transmission will be either overfilled or underfilled. A 2' level placed on the door sill plate is best, but a smaller one will suffice.
The entire system holds 13.24 quarts. A normal pan removal will require 6.5 quarts to refill. Short of pulling the transmission and draining the torque converter, you can't get more than 50% new fluid. I recommend the AC Delco Dexron VI, since it's an exact match to the factory fill of the remaining 6.5 quarts still in the car.
Purchase from your local dealer, online dealer, or forum dealer.
PN 88865601 DEXRON VI -- $6-7 (buy 7 quarts)
PN 24236931 FILTER -- $30-35
PN 24224781 PAN GASKET -- $ 12-15
You may not need the pan gasket. I've had mine off 4 times and reused it each time. If you opt not to buy one, just be careful not to damage the original during the process.
The "clean" way is to suction or siphon out most of the fluid from the fill port before you drop the pan. If you only use the drain plug in the pan, there will be several quarts remaining in the pan and it could get real messy when it comes off. The fill port is high on the right side near the front of the case. The plug is similar to a push pin connector. Pull up the smaller center pin and then pull out the plug. Long handle 80* angled needle nose pliers work for me. If it's dirty in the area of the plug, clean it well before removal.
Accessing the pan bolts is easier if you first loosen the nuts on the bottom of the transmission mounts and raise it slightly. Don't go higher than necessary and keep the nuts at least on a couple threads. Torque to 37 lb/ft when the job is completed.
After you remove the pan, pull straight down on the filter to remove it.
While the pan is out, remove the magnet that resides in the 3 pointed star area and clean everything, including the gasket. Put the magnet back in, of course.
This first photo shows the tightening sequence for the pan bolts and the filter. Pan bolt torque is 80 lb/in. Do not over-tighten.
Also note item 5 is a seal which is packaged with the filter.
I made a tool to remove and install the seal. It's a 1/4-20 x 5 bolt (threaded rod works too) with a thick 1" washer ground down to .945-.950 with about a 10* taper on the removal end and a 1.25 fender washer plus three 1" fender washers on the install end. To remove the seal push the washer through the seal and then pull the tool out and the seal will come out too. The install is self evident by the way the seal fits on the tool, but make sure it's fully seated. When you install the filter, put a little trans fluid on the neck and push it up until it hits the flange of the seal.
Now the fun part is the fill and check procedure. I suggest using one of those inexpensive pumps that screw into the one quart bottles.
Follow these instructions exactly in the order written.
1. Put all 7 quarts of fluid in the fill port and replace the fill plug and push the center pin down until it's flush.
2. Start the engine (DO NOT SHUT IT OFF DURING #6 or #7) and bring the trans temp up to between 86 and 122 degrees at idle speed. I prefer to shoot for 100, since it gives enough time to perform everything else before it gets too hot.
3. While sitting in the car with your foot on the brake, shift into each gear selection and pause 3-5 seconds before moving to the next gear. When you reach SPORT, then shift back to PARK.
4. Let the engine idle for 1 minute.
5. Recheck the temperature. 104* is ideal. If you are close to 120*, it's better to stop at this point and start over at #2 after it cools down.
6. Remove the drain plug in the bottom of the pan and let the excess fluid drain out until it slows to a trickle. It should drain out about 1/2 quart. If nothing comes out, you need to put the drain plug in and start way back at #1 and add one more quart.
7. Replace the drain plug and torque it to 18 lb ft.
8. Shut the engine off. You have successfully finished a fluid and filter change on your 6l80 transmission.
great idea; the last time I did it I didnt have a tool to remove the seal. I always wondered if it took some overpriced one use factory item to get the darned thing out
btw After checking every auto store and physically inspecting every available 6l80 filter - I found the autozone/duralast trans filter looks exactly like the factory one except its missing the GM part # markings (for obvious reasons); none of the other brands from oreilly, napa, or advance were even close. iirc its roughly 30 bucks and one of those items thats usually in stock at most locations
But here's a question - If you want to try to get as much of the old fluid out as possible can you:
1) drop the pan and roughly refill the amount you took out
2) disconnect a cooler line, start the car and run it till the fluid coming out of the cooler line changes color to the color of the nice new fluid, or until you have almost pumped the pan dry - then fill again till the fluid changes color - then do the final fill to the correct level ???
The way I understand things - On the older style GM auto trannys - the cooler was almost the last thing the fluid went through before it ended up back in the pan - so if you started with fresh fluid in the pan - and had the tranny "pump" the fluid out via the cooler line - you would essentially flush the majority of the fluid out. I don't know if that is still the case with the 6L80 and newer trannys...
But here's a question - If you want to try to get as much of the old fluid out as possible can you:
1) drop the pan and roughly refill the amount you took out
2) disconnect a cooler line, start the car and run it till the fluid coming out of the cooler line changes color to the color of the nice new fluid, or until you have almost pumped the pan dry - then fill again till the fluid changes color - then do the final fill to the correct level ???
The way I understand things - On the older style GM auto trannys - the cooler was almost the last thing the fluid went through before it ended up back in the pan - so if you started with fresh fluid in the pan - and had the tranny "pump" the fluid out via the cooler line - you would essentially flush the majority of the fluid out. I don't know if that is still the case with the 6L80 and newer trannys...
The OEM cooler and lines hold less than 1/2 quart and the flow is not positive. The majority of remaining fluid (about 6 quarts) is in the TC. But yes, if you wanted to have a larger percentage of new fluid, you could drive the car for some period to thoroughly mix the initial change with that which remained and then drain and repeat the process as many times as you wanted with diminishing returns.
Just 2 little things that can help as notes. Cement mixer tubs are great for catching fluid doing a trans service. And if you have an aftermarket converter and drag race an extra .5-.75 quart of fluid helps with the car nosing over on the launch.
Nice write up.
I used a 2x4 on the diff to jack the trans up enough to get to the rear bolts. I had to modify a socket and swivel.
How did you have to modify the socket and swivel? Do you think I would have to modify a 10mm swivel socket ( the one in the middle) or would the bottom wobble extension give the clearance needed without tool modification? Does the top socket and swivel look like the tool you modified? I would go buy a cheepie socket or swivel if you think these would not work without modification.
How did you have to modify the socket and swivel? Do you think I would have to modify a 10mm swivel socket ( the one in the middle) or would the bottom wobble extension give the clearance needed without tool modification? Does the top socket and swivel look like the tool you modified? I would go buy a cheepie socket or swivel if you think these would not work without modification.
I milled both ends of the socket and one end of the swivel (grinder is fine as well). The head of the bolt bottoms out in the socket and the male end of the 1/4 drive bottoms out in the other end. I also milled the female and of the swivel the same way. Assembled length is 1.550". End of socket to 1st swivel joint is .925". Hope this helps.
I milled both ends of the socket and one end of the swivel (grinder is fine as well). The head of the bolt bottoms out in the socket and the male end of the 1/4 drive bottoms out in the other end. I also milled the female and of the swivel the same way. Assembled length is 1.550". End of socket to 1st swivel joint is .925". Hope this helps.
THANKS.
Was the purpose of grinding the socket end to shorten the socket end to first swivel or OAL? I measured the swivel socket and it is 1.268" OAL and the end of socket to first swivel is .463". Any reason that this would not work? SnapOn TMUSM10
Was the purpose of grinding the socket end to shorten the socket end to first swivel or OAL? I measured the swivel socket and it is 1.268" OAL and the end of socket to first swivel is .463". Any reason that this would not work?
Looks like it should work fine. Wish I had one of those in the first place
A suggestion (maybe it'll help some): highlight the "lb.in." and "lb.ft." Too easy for some to "read"...."Aw, it's just X lb.ft." when, in fact, it's lb.in., or vice versa.
I finally had time to do my transmission service. This thread was MOST helpful and complete. The Snap-On 10mm swivel socket (mentioned in my earlier post) worked perfectly to reach the back bolts . Snap-On TMUSM10.
I did run into one area that I had problems with. Removing the seal for the transmission filter. I made the seal removal tool (described in original post) but it would not budge. After several attempts the rubber on the seal was damaged, so NOT changing it was NOT an option. I used a screwdriver and caught the edge of the seal's metal ring and bent it inwards to relieve the pressure and removed it with a pair of needle nosed vice grips. Not high tech but the seal was out. The diameter of the tapered end of the tool I made, at its largest, is .949".
Installation of the new seal was not a problem. I don't know if replacing the seal was necessary. There is one torque setting not mentioned. The torque for the transmission mounts is 37 ft/lb.
My vehicle is a C6 09 vert with 61k miles. It shifts MUCH cleaner. I am glad I didn't wait for 100k.
Last edited by Obiwan-J.M.; 12-20-2017 at 11:58 AM.
Reason: corrections
Wow... that's a lot to take in. Thanks! NOW... since I have ordered the B&M 13,000BTU cooler already, would you recommend running it in series with the radiator cooler, or as a stand-alone? I live in a fairly mild climate but the mornings can be very cold. Haven't gone racing at all, yet...
Just installed B&M cooler on mine. I ran it after the rad trans cooler. I live in a climate that gets cold in the mornings. The B & M cooler has a built in bypass for cold fluid to help it warm up before running thru aux cooler.
Just installed B&M cooler on mine. I ran it after the rad trans cooler. I live in a climate that gets cold in the mornings. The B & M cooler has a built in bypass for cold fluid to help it warm up before running thru aux cooler.
Could you post the part number please. I currently have an external thermostat bypass, but it really doesn't work very well, because the pump is not a positive flow and it takes too long to open the valve.
It was a b&m cooler 70273 with built in bypass. When the fluid is cold it cannot enter the cooler and goes back to tje transmission.
That's exactly the same cooler I have and nowhere on the sales documentation or installation instructions does it mention a bypass. I see no mention of it on Summit Racing's site either. Could you post up anything you have that tells more about it. I'm interested enough to buy one to see if it works for me.
Thanks.
10-05-2016, 10:53 PM
6l80 transmission fluid/filter change instructions
The fill port is high on the right side near the front of the case. The plug is similar to a push pin connector. Pull up the smaller center pin and then pull out the plug. Long handle 80* angled needle nose pliers work for me. If it's dirty in the area of the plug, clean it well before removal.
