Rear end fluid

[78 squarebody]

I'm changing out my rear diff cover gasket i was wondering what's a good fluid to use for a stock 12 bolt on my 78 k10 thank you

 

[bucket]

80/90 gear oil. Pick any brand.

If you can't get your fill plug out, you can just put the gear oil in ziploc baggies and stuff them in there before you put the cover back on.

 

[Grit dog]

80/90 gear oil. Pick any brand.

If you can't get your fill plug out, you can just put the gear oil in ziploc baggies and stuff them in there before you put the cover back on.

Damn I never thought of that! That’s a great idea. I finally bought a qt of some overpriced gear lube in the squeeze bag when I changed the fluid in the bitchin Camaro because it was that hard to get to even with a long piece of hose taped to the nozzle. I would have done that in a heartbeat.
How many sandwich bags of gear lube does a 12 bolt take? Lol

 

[Edelbrock]

80/90 gear oil. Pick any brand.

If you can't get your fill plug out, you can just put the gear oil in ziploc baggies and stuff them in there before you put the cover back on.

Interesting idea. I supposed that would work. But how would you check the fluid level later? And if you are going to fix the stuck plug, it would be easier to do when the diff cover is off. But still, the ziplock bag thing is an interesting idea. I would not do it if it could be avoided, but I still support the idea and would consider it if it needed to be done.

 

[bucket]

Interesting idea. I supposed that would work. But how would you check the fluid level later? And if you are going to fix the stuck plug, it would be easier to do when the diff cover is off. But still, the ziplock bag thing is an interesting idea. I would not do it if it could be avoided, but I still support the idea and would consider it if it needed to be done.

If you want to check the fluid later, then you either have to pull the cover again, or just bite the bullet and deal with the plug. But if the axle doesn't have any leaks, it really doesn't need checked.

Back around 2018 or so, my '00 Burb killed an axle seal and leaked most of the fluid out. The fill plug was seized and baddy stripped out by the previous owner. So I pulled the cover and put in the baggies of fluid. I also ordered a fancy aluminum diff cover that included a fill and drain plug, to install as a proper fix. Well here we are 7-ish years later and that fancy diff cover is still in the box, on a shelf in the garage.

 

[Edelbrock]

The plastic bag thing is an interesting idea. I wonder that other stuff would work. Maybe lift the rear end of the truck or park on a steep "down hill" road. There are also various different types of drain plugs that have valves to stoop the flow. You could pump the fluid into the diff through the "valved" drain plug.

Although if the diff cover is already off, there are many ways to get the plug out, including adding a secondary fill plug.

 

[bucket]

The plastic bag thing is an interesting idea. I wonder that other stuff would work. Maybe lift the rear end of the truck or park on a steep "down hill" road. There are also various different types of drain plugs that have valves to stoop the flow. You could pump the fluid into the diff through the "valved" drain plug.

Although if the diff cover is already off, there are many ways to get the plug out, including adding a secondary fill plug.

The fill plug of most GM diffs is ahead of the carrier. Having just the cover off doesn't aid in the repair of a stripped and seized fill plug.

 

[Edelbrock]

The fill plug of most GM diffs is ahead of the carrier. Having just the cover off doesn't aid in the repair of a stripped and seized fill plug.

Ah. Good point, I forgot about the location. I guess the only advantage to having the diff cover off would be to recover metal shavings if you drill out and re-tap the fill plug, or to add a secondary fill plug on the cover.

 

[Moodyalaskan]

If you "had to" because of buggered up plug, you could fill it with required amount of gear lube thru the vent opening. Use the largest meat injector you can fit into the hole leaving a space for air to escape. Slow but doable.

 

[Sad Sack]

I'm not the brightest bulb on the tree but just a thought, can a bolt be welded to the plug and ratcheted out?

 

[Ricko1966]

I'd just drill a hole in the cover tac a piece of flat stock or a nut on the inside of the cover. The nut or flat stock doesn't need a full weld, use a bolt with a sealing washer on the outside to prevent leaks. I could tell you how to do it with no welder or torch if absolutely necessary. Eye ball height for future level check. Also hole and bolt do not need to be big. Big enough for the plastic nozzle on the bottle.