Correct way to service 2024 l8t allison trans?

[Chuck FB]

2 hours ago, No F-bdy Bs said:

I've considered doing that. Definitely not a bad idea, especially if your roads see salt. 30min and some anti-sieze could save a lot of grief in the future. 

I made a note of doing that myself just now on my growing list of items to do or check over on my truck ... the list is getting longer all the time. Unfortunately I have to contend with both salt and calcium chloride, substances that make for repeat customers to the new section of a vehicle dealership.

[Chuck FB]

Lately I had dropped in at a locally owned transmission shop to see what if any thoughts they had on the 10L1000 issues and he said as of yet they haven't had a truck come there for a transmission issue because the theme has been the GM dealers around here anyway are getting the problem trucks because the valve bodies are hard to get even for the dealer and a lot of the trucks would still have warranty ... yet that is. However he has had some customers bring their trucks to have the fluid changed and has changed the fluid on the gas version and has dropped the exhaust to get at the pan. They were not flushing the trans because of concern of breaking up some buildup pushing some crap into it so just changing the fluid in the pan and a new filter. He said labour makes the job expensive as the total bill he has been charging is 900.00. This is in Canada and labour rates are stupid high and I had not asked if he changes the pan gasket but I found out the dealer list price is 139.00 on the gasket ( they might be able to be reused if not damaged ) and the filter kit is 115.00 and the oil would be 153.00 for 10 quarts of oil. So a maximum of over 400.00 in parts going by that but the GM dealer will knock some off the prices if the truck was purchased there and by buying the oil by the 12 quart case they drop the price quite a bit so my price at the dealer for the parts was around 300.00 . I never did ask at the dealer what they charge for the same service and the dealer did not have a pan gasket in stock which makes me wonder if the dealer is re using the gasket, they had the filter and oil in stock. 

 

The owner of the trans shop recommended ideally doing a pan drop every 25000 miles if towing and from what trucks he has changed the oil on he figured it seems to be around the 9.5 quarts required but like he said its important to go through all the bs of warming it up to the temp specs to check the level because he found that oil seems to expand a lot and of course as its hotter it drains back to the pan faster anyway. 

[EXSlider400]

This may seem crazy, but has anyone rerouted the exhaust crossover away from the pan? I was thinking about doing this on 2025 2500. I did the exhaust disconnect on a 2019 6.2 with 10-speed with over 100k miles and it was a pain and assume the 2500 will be very similar. 

[64BAwagon]

I paid around $5 qt for the GM ULV fluid from Rockauto. I got the filter for less than $35 (obviously US$)

as far as the pan gasket its reusable and should be good for several pan drops. I have all the stuff for my 2024 gasser but I sold it with less than 12,000 miles so I never had to do it. It does however look like the trans crossover bolts could be backed out and the trans jacked up enough to clear the exhaust. My plan was to install a drain plug or buy a Dorman pan with the plug in it (about $150 on Rockauto)

As far as refilling I bought a m18 nipple that screws into  the fill plug on the side of the case. It would allow me to run a hose to the normal dipstick area and fill the trans that way. If you use a clean pan you can measure the amount of fluid that drains out and replace that amount. 

[Chuck FB]

19 minutes ago, 64BAwagon said:

I paid around $5 qt for the GM ULV fluid from Rockauto. I got the filter for less than $35 (obviously US$)

as far as the pan gasket its reusable and should be good for several pan drops. I have all the stuff for my 2024 gasser but I sold it with less than 12,000 miles so I never had to do it. It does however look like the trans crossover bolts could be backed out and the trans jacked up enough to clear the exhaust. My plan was to install a drain plug or buy a Dorman pan with the plug in it (about $150 on Rockauto)

As far as refilling I bought a m18 nipple that screws into  the fill plug on the side of the case. It would allow me to run a hose to the normal dipstick area and fill the trans that way. If you use a clean pan you can measure the amount of fluid that drains out and replace that amount. 

I've talked to friends that have ordered items from Rock Auto that live here in Alberta but the reason they bought the parts through the states was that it was for vintage vehicles that they couldn't source the parts through a Canadian supplier that had could get them or had such an outrageous price. For the fun of it some time back I did a pretend order through Rock Auto to see what it claimed the price would be and by the time the exchange was done and the huge issue being the shipping, it made no sense at all to order from them unfortunately, also I was not entirely sure they would even ship oil or certain items like that up here because of it being a hazard product. So locally I had priced out the Delco ULV oil as one automotive supplier I am aware of even handles it and their price was just as high as the full list price at the dealership, the trans filter was about the same as what my so called "good" price was at the dealership. Basically the theme is we get bent over the counter and pounded hard with no offering of dielectric silicone lube to lessen the pain !. They know that ULV is in demand as they also sell the Delco Vi and its a fair bit cheaper then at the dealer. 

 

I had seen a video a guy did not that long ago where he undid an exhaust bracket hanger that I think bolts to the trans, then pulled out one of the rubber hangers back near the pipe joint. He did not loosen off any exhaust nuts though, on the manifolds or at that connector joint which I believe put way too much stress on the piping joints as he use a ratchet strap to literally suck down the exhaust pipe until it contacted the frame cross member at the back of the trans. By doing that he was able to just get the pan out but it was so tight that even the thickness of the gasket would not fit in that gap as he went to fit the pan back up ( he chose to use a new gasket ) and the pan with the gasket laying on it would not fit as an assembly so had to refit the gasket after the edge of the pan passed by the tightest area. The reason he did not undo the exhaust nuts was because of the risk of twisting off studs and basically a whole experiment to see if it could be done that way. As to the rear of the trans being lifted, I wonder if that would be more than the exhaust to engine manifold joints would like. That same bracket on the trans would have to be undone as otherwise the trans would be lifting the exhaust up, I haven't looked closely at that assembly myself. But in that video it was quite evident that without doing anything there was no way his pan was going to be able to be pulled out of there, all GM had to do was design the piping a bit differently and would make life easier but they probably really didn't care as vehicles these days don't seem to be made with working on them easily, instead make it complicated so the dealership gets the work. That's the bonus of the diesel version of this trans, you will be able to drop the pan without all this hassle. 

 

Speaking of the Dorman pan, the aftermarket parts supplier locally has Dorman P/N 265-587 listed for this truck and the price here is 552.00 in Canadian funds of course. 

[64BAwagon]

Oh man, you guys are getting hosed on prices. Thats sad

 

[Chuck FB]

Its typically tended to be that theme over the years to an extent but I would say its gotten a fair bit worse with things in general these last years and part of it is our scum bag government with outside the country ties that's destroying our country from within and our dollar with it. There is no good reason for us to be in the situation we are and yet ... here we are. 

[Chuck FB]

On 6/15/2025 at 12:05 PM, 64BAwagon said:

I paid around $5 qt for the GM ULV fluid from Rockauto. I got the filter for less than $35 (obviously US$)

as far as the pan gasket its reusable and should be good for several pan drops. I have all the stuff for my 2024 gasser but I sold it with less than 12,000 miles so I never had to do it. It does however look like the trans crossover bolts could be backed out and the trans jacked up enough to clear the exhaust. My plan was to install a drain plug or buy a Dorman pan with the plug in it (about $150 on Rockauto)

As far as refilling I bought a m18 nipple that screws into  the fill plug on the side of the case. It would allow me to run a hose to the normal dipstick area and fill the trans that way. If you use a clean pan you can measure the amount of fluid that drains out and replace that amount. 

I was thinking about the M18 nipple you bought, was that a straight nipple with a barbed end ( and not a 90 degree fitting ) and do you know what hose size your fitting was made for as the larger a barb size one could get assuming it would work in that confined space, the faster the flow into the trans and easier on the upper/engine end to adapt a funnel to pour the oil into the hose.

 

On the left side of the case there is supposed to be a filler plug that faces up and is higher up on the case as the drawing shows, I haven't looked much to find that one and probably need a mirror to locate it and the challenge there would be to clean the area up good before removing that M18 plug if used but the hose would not have to have a sharp bend, that could be the possible issue with the right side plug that is on the side of the case. Wouldn't really know until a fitting and hose was set up on the right side to see how it worked out. 

 

Yes I could buy a fancy air pressured unit that I could see the volume of oil going in or instead buy a dedicated five gallon pail pump and dump in quarts into the pail and pump it in by hand, have pumped quite a lot of gear oil out of five gallon pails over the years and certainly that would do the trick too. Of course this is all nit picking stuff relative to that exhaust to pan clearance issue which turns a bit of a job into something many times more complicated for no good purpose. 

Edited June 25, 2025 by Chuck FB