Rear differential level on 2024 3500 L8T

[Chuck FB]

2 hours ago, 64BAwagon said:

I use a rattle can of FF for the doors and just use the straw through  the drain holes. Some are obstructed by the rubber seal so you have to look closely for them.  Best done on a hot day when you can let them drip for a while. It migrates well enough so coverage is good. No way I want to pull door panels on a new truck. 

I picked the Blaster up locally for $12 gallon, and had 2 other orders cancelled at other stores. I really wanted to score a couple 5 gal pails but never could pull it off. 

You prompted me to have another look at my doors and realized a couple of things that I had not clued into before. One was that some of the drain holes, the only ones I have are on either end of each door, some had some paint partial obstruction or something of that nature in the way visually so the hole looked like a crack, and yes prior I had found the holes that are being obscured by the lower weather stripping and have to lift that up at the end of the stripping to access those holes. However what I had not realized is that the lower and the main door weather stripping is clipped on, I had assumed they were glued on for some reason and had never tried pulling on it some along its length to realize its merely clipped on, that was my "duh" moment !. Now I don't know if those clips would break if pulled on or if there is a technique to pull them without ruining the strip in the process but that would allow access to spaced holes along the length of the doors if if was desirable to do so.

 

However going back to what you did and gather you only used the two per door drain holes to accomplish this, were you parking the truck in an attitude that allowed gravity to work for you such that you sprayed in one door drain hole and the FF made its way along the seam to drip out of the opposite hole or did you just spray a bunch in from both ends and let it do its own thing to migrate along. And good point about the temp as FF isn't exactly a viscus product at cooler temps to flow well. Now weather i should or not I do use FF for door hinges, I find white grease for example to dry up/harden and becomes useless.

 

You got one smoking deal on the blaster, no wonder you were on the hunt for some more but to no avail. I pay more here for 1 aerosol can of blaster than you were for a gallon of product, no wonder I feel I get ripped a new one every time I turn around up here !.

[Pryme]

1 hour ago, Chuck FB said:

You prompted me to have another look at my doors and realized a couple of things that I had not clued into before. One was that some of the drain holes, the only ones I have are on either end of each door, some had some paint partial obstruction or something of that nature in the way visually so the hole looked like a crack, and yes prior I had found the holes that are being obscured by the lower weather stripping and have to lift that up at the end of the stripping to access those holes. However what I had not realized is that the lower and the main door weather stripping is clipped on, I had assumed they were glued on for some reason and had never tried pulling on it some along its length to realize its merely clipped on, that was my "duh" moment !. Now I don't know if those clips would break if pulled on or if there is a technique to pull them without ruining the strip in the process but that would allow access to spaced holes along the length of the doors if if was desirable to do so.

 

However going back to what you did and gather you only used the two per door drain holes to accomplish this, were you parking the truck in an attitude that allowed gravity to work for you such that you sprayed in one door drain hole and the FF made its way along the seam to drip out of the opposite hole or did you just spray a bunch in from both ends and let it do its own thing to migrate along. And good point about the temp as FF isn't exactly a viscus product at cooler temps to flow well. Now weather i should or not I do use FF for door hinges, I find white grease for example to dry up/harden and becomes useless.

 

You got one smoking deal on the blaster, no wonder you were on the hunt for some more but to no avail. I pay more here for 1 aerosol can of blaster than you were for a gallon of product, no wonder I feel I get ripped a new one every time I turn around up here !.

I wouldn’t spray FF on the door hinges unless you want to accelerate wear. Probably take 30 years to have a hinge rust out they are protected well and painted. If anything, something like a dry graphite lube that doesn’t attract grit. 

[Chuck FB]

40 minutes ago, Pryme said:

I wouldn’t spray FF on the door hinges unless you want to accelerate wear. Probably take 30 years to have a hinge rust out they are protected well and painted. If anything, something like a dry graphite lube that doesn’t attract grit. 

I see your point and yet I know with the various vehicles on the farm its the ones that were neglected or ones we bought well used that I know where neglected to lube up, they have hinge issues. Now I am not claiming this will have issues if not lubed but I never had issues with vehicles I do lube on occasion. All I have to do is go to the local RItchie bros sale site and open some doors on company trucks that have seen their fair share of use and boy is that a wakeup to what abused vehicles end up like ( picture having to lift the door up to latch it LOL )

[Chuck FB]

On 4/27/2025 at 6:14 AM, 64BAwagon said:

I use a rattle can of FF for the doors and just use the straw through  the drain holes. Some are obstructed by the rubber seal so you have to look closely for them.  Best done on a hot day when you can let them drip for a while. It migrates well enough so coverage is good. No way I want to pull door panels on a new truck. 

I picked the Blaster up locally for $12 gallon, and had 2 other orders cancelled at other stores. I really wanted to score a couple 5 gal pails but never could pull it off. 

The weather was warm yesterday so I went at it with the doors to get the bottom seams covered, I imagine I used more FF than I needed as there is no visual when injecting a product into a blind spot. I did remove the lower weather stripping on the doors but its hard not to compromise the odd clip in the process and I bet they don't sell them separate from the weather stripping so that was a debatable method for that reason but did allow for complete coverage. I can see that maybe if one had a kit with the small diameter long adapter hose for the FF cans, that might work ok to reach in from that single slotted hole behind each strip on a door "maybe". I'm pretty sure I've drowned the bottom seam though with all the antics I went through which was the goal, some of those end formed holes were very tight to get the straw into but those are the lowest holes on the doors and certainly where excess dribbled out.

[64BAwagon]

We had a (finally) warm 70 degree sunny day yesterday so I spent the afternoon doing an oil change on the truck (it only had 200 miles but someone had been idling it a lot before I got it because it had 10 hrs on the engine)  I always do a change when they are new. 11 qts of Mobil Delvac extreme and a Champion labs PH10063 (same as the AC) went into it along with the Fumoto valve. 

Since I had it on the ramps I decided to rustproof the rockers inside and out so I fired up the compressor and spent the next couple of hours protecting my investment.  I have one or 2 little things to do and the truck will all set. 

[Pryme]

1 hour ago, 64BAwagon said:

We had a (finally) warm 70 degree sunny day yesterday so I spent the afternoon doing an oil change on the truck (it only had 200 miles but someone had been idling it a lot before I got it because it had 10 hrs on the engine)  I always do a change when they are new. 11 qts of Mobil Delvac extreme and a Champion labs PH10063 (same as the AC) went into it along with the Fumoto valve. 

Since I had it on the ramps I decided to rustproof the rockers inside and out so I fired up the compressor and spent the next couple of hours protecting my investment.  I have one or 2 little things to do and the truck will all set. 

Are you using your sg3 in this truck? I know it has some diesel features. 

[Chuck FB]

5 hours ago, 64BAwagon said:

We had a (finally) warm 70 degree sunny day yesterday so I spent the afternoon doing an oil change on the truck (it only had 200 miles but someone had been idling it a lot before I got it because it had 10 hrs on the engine)  I always do a change when they are new. 11 qts of Mobil Delvac extreme and a Champion labs PH10063 (same as the AC) went into it along with the Fumoto valve. 

Since I had it on the ramps I decided to rustproof the rockers inside and out so I fired up the compressor and spent the next couple of hours protecting my investment.  I have one or 2 little things to do and the truck will all set. 

Oh, you used the "good stuff", although different engines of course but in the last number of years have been using 15W-40 for spring to fall equipment and is the Mobil 1300 Super, and for diesels that get used during the winter I go with the Delvac 0W-40. I only have one tractor that has the EGR and I find that a total piss off with the oil getting black within one days use but I don't put near the recommended hours on the oil before I drop it, stupid regurgitating ****** ....

 

I put the Fumoto or I think it was that brand on my highway tractors, the factory drains as well as the Fumoto are on the side of the pan, this way I can put the 90 degree hose on and direct it properly, I dreaded the job before putting the drains on them.

 

On your rockers, which plugs did you pull to access, ones on the side or any on the bottom as well ?

[64BAwagon]

I pulled the oval ones on the bottom as well as the two bigger size ones on the vertical inner rocker. I carpet bombed the rockers. Cheap insurance against a very expensive truck. I rarely drive my truck up here in the winter and my goal for years has been to not be in the salt belt during the heart of the winter. 

I have used the Delvac 1300 in the past as well as all the trucks at work and its proven itself many times. I am running the Extreme due to Walmart having it at a great price and a solid rebate. I still have a 5 gal pail and 2 gallon jugs in inventory. 

Edited May 8, 2025 by 64BAwagon

[64BAwagon]

5 hours ago, Pryme said:

Are you using your sg3 in this truck? I know it has some diesel features. 

Yes. I have the pages reconfigured. It was an easy swap. I created the 3 pages with some core monitors and then specific ones on each. Page 1 is general use, page 2 is towing and page 3 is for stuff to monitor just because I can. That way I can scroll; through them when on a long trip. I have found the boost gauge valuable for mileage when towing

[Aimatdeer]

Did you hit all the fittings in the front end with grease?

Mine appeared dry.

[64BAwagon]

10 hours ago, Aimatdeer said:

Did you hit all the fittings in the front end with grease?

Mine appeared dry.

Yes, I did grease the fittings on the front end by adding a few pumps of grease to each. 

This has been discussed widely in a bunch of places. I know for a fact that all of the parts on the front end do in fact have grease in them. When the supplier manufactures the parts they put grease on the joints during assembly. The fact that there isnt any additional grease added through the fitting is not an indication that the part has not been greased. 

I added a 3 or 4 pumps to the ball joints and tie rod ends, the Pitman arm and idler only took one each. I only put about 5k miles a year on my truck so I am good until next spring. 

[Another JR]

On 4/26/2025 at 7:48 AM, the8rotor said:

Looking to drain and fill the front and rear diffs on my 2024 gasser. Can someone share torque specs for both front and rear diff covers? I have fluid type and capacities, cannot find torque specs to save my life. 

I know this question is old but I found a good video on changing the fluids and the poster included the torque values. I figure it might help somebody. 
 

 

 

I changed the rear differential oil on my 2021 3500HD gas truck today. The truck is at 15k miles. The fluid level before I drained it was about an inch below the fill port. I measured 2.5 quarts drained, but some fluid stays on the surfaces.  I tipped the axle side to side with a floor jack to make sure i didn’t have too much residual oil left inside. There was no visible sparkle in the oil, but there was a decent amount of black powder on the magnet and the cover. I have not towed heavy with this truck - it hauls a light slide-in camper. 
 

It took 3.5 quarts to get the level to about 0.4 inches below the fill port. I used Amsoil Severe Gear 75w-90. 

[Chuck FB]

5 hours ago, Another JR said:

I know this question is old but I found a good video on changing the fluids and the poster included the torque values. I figure it might help somebody. 
 

 

 

I changed the rear differential oil on my 2021 3500HD gas truck today. The truck is at 15k miles. The fluid level before I drained it was about an inch below the fill port. I measured 2.5 quarts drained, but some fluid stays on the surfaces.  I tipped the axle side to side with a floor jack to make sure i didn’t have too much residual oil left inside. There was no visible sparkle in the oil, but there was a decent amount of black powder on the magnet and the cover. I have not towed heavy with this truck - it hauls a light slide-in camper. 
 

It took 3.5 quarts to get the level to about 0.4 inches below the fill port. I used Amsoil Severe Gear 75w-90. 

 

That goes to show even a more lightly used truck and relatively few miles on that factory oil, the break in process creates enough wear metals to show up like that. I'll see what I get around to dropping oil wise this summer as I won't have that kind of miles on the truck and may not be worth doing yet but being early is better than being too late for sure. It was only because of this forum in coming across it and before I had signed up to be a member that I had seen a thread where someone was mentioning the whole issue around the rear diff on the GM trucks having low oil from the factory and so right after I bought my truck I wet through all the drive line fluids including the transmission which is a pain due to the procedure and then if nothing comes out have to let the exhaust cool to add fluid and do it all over again by warming it up. Anyway it was ok but my front diff was a bit low ( from being full that is ), transfer case also a bit low and did add oil to both of them but what really stood out was the rear diff as it was just as you found, a good inch low and so I topped that up to full. 

 

That particular video, I had not come across it as I was looking for that same information and then someone else on here found it and posted it a little while back but I know how things like that go, it gets buried and hard to find so always good to bring good information back into the spotlight to help and remind one to make a point of checking the levels or changing the driveline oils. It still pisses me off that GM quit making the front and rear diffs with drain plugs as its easier to drop the diffs oils on a highway tractor that holds 6 gallons of oil than it is on a pickup to change the diff oil !. 

[Chuck FB]

12 hours ago, Another JR said:

I know this question is old but I found a good video on changing the fluids and the poster included the torque values. I figure it might help somebody. 
 

 

 

I changed the rear differential oil on my 2021 3500HD gas truck today. The truck is at 15k miles. The fluid level before I drained it was about an inch below the fill port. I measured 2.5 quarts drained, but some fluid stays on the surfaces.  I tipped the axle side to side with a floor jack to make sure i didn’t have too much residual oil left inside. There was no visible sparkle in the oil, but there was a decent amount of black powder on the magnet and the cover. I have not towed heavy with this truck - it hauls a light slide-in camper. 
 

It took 3.5 quarts to get the level to about 0.4 inches below the fill port. I used Amsoil Severe Gear 75w-90. 

 

I thought of it after my comment last night, was the Amsoil you used in the 1 quart bottles and if so did you have a bottle pump or one of those bottle hose adapters to then hold the bottle above and upside down to pour in the oil. I had bought some of those squeeze packs ( of course they end up costing more ) of the severe gear 75W-90 for when I do change the diff oil and the only reason I bought them was to see if I liked using them or if it was not worth the premium price. The problem with a squeeze pack is that there is no way of knowing how much is taken out or still in the pack unlike a bottle that is easy to see with the clear strip and markings that most bottles today have. It was the same situation years ago when plastic oil containers had no markings or if they did they didn't have a clear strip to visually see the level. 

 

Also another item and as per the video you linked, he went through the process of using new thread locker on the cover bolts and while it does seem odd that a diff cover should require thread locker, what was your thoughts on that and if you used some blue thread locker for example or just cleaned ( solvent ) the bolts if needed and left on the old thread locker residue as they were and reinstalled them. With 29 lb-ft of torque on the bolts, I have a hard time visualizing the bolts backing out, it can't be as critical as you doing jobs like installing a prop on an aircraft and having to wire fasten every bolt head or do GM diffs vibrate that much ? LOL. 

Edited January 10 by Chuck FB

[Another JR]

3 hours ago, Chuck FB said:

 

I thought of it after my comment last night, was the Amsoil you used in the 1 quart bottles and if so did you have a bottle pump or one of those bottle hose adapters to then hold the bottle above and upside down to pour in the oil. I had bought some of those squeeze packs ( of course they end up costing more ) of the severe gear 75W-90 for when I do change the diff oil and the only reason I bought them was to see if I liked using them or if it was not worth the premium price. The problem with a squeeze pack is that there is no way of knowing how much is taken out or still in the pack unlike a bottle that is easy to see with the clear strip and markings that most bottles today have. It was the same situation years ago when plastic oil containers had no markings or if they did they didn't have a clear strip to visually see the level. 

 

Also another item and as per the video you linked, he went through the process of using new thread locker on the cover bolts and while it does seem odd that a diff cover should require thread locker, what was your thoughts on that and if you used some blue thread locker for example or just cleaned ( solvent ) the bolts if needed and left on the old thread locker residue as they were and reinstalled them. With 29 lb-ft of torque on the bolts, I have a hard time visualizing the bolts backing out, it can't be as critical as you doing jobs like installing a prop on an aircraft and having to wire fasten every bolt head or do GM diffs vibrate that much ? LOL. 

I bought the 1 quart squeeze packages. They worked well. I drained the empties into the partial one at the end and only got a teaspoon or so out of each.  The access is pretty open for the rear differential even without lowering the spare tire.