C-2 Muncie transmission oil recommendation

[Michael K.]

I understand we only want to use GL-4 lubricant in Muncie 4 speed transmissions. I was told ACDELCO Dexron SAE 75W-90 Gear oil is a good product for these applications, good lubrication without damaging the synchronizer teeth. However, the label does not indicate GL-4 or GL-5. I couldn't find anything on this in the archives. Thanks, Michael Kalogridis

[Joe L.]

Re: C-2 Muncie transmission oil recommendation

I understand we only want to use GL-4 lubricant in Muncie 4 speed transmissions. I was told ACDELCO Dexron SAE 75W-90 Gear oil is a good product for these applications, good lubrication without damaging the synchronizer teeth. However, the label does not indicate GL-4 or GL-5. I couldn't find anything on this in the archives. Thanks, Michael Kalogridis

Michael-------


I'd recommend going with GM #88900401, aka Delco 10-4016. This is a heavy duty, synthetic GL-5 lubricant. These days, if you find any GL-4 lubricant on the market at all, it will be some really low quality, "budget"-branded stuff.

[Frank D.]

Re: C-2 Muncie transmission oil recommendation

I use Amsoil Synthetic 75w-90w Manual Transmission GL-4 lube. Which I prob will get flamed for.
It cleared up a slight clash when downshifting from 3rd to 2nd in my VERY early 63 Muncie.
Going on 4-1/2 years now...

[David K.]

[Duke W.]

Re: C-2 Muncie transmission oil recommendation

The original spec was Mil-L-2105 - same as the axle... look at your owner's/service manuals and AMA specs. The mil spec was canceled about 20 years ago and replaced with the commercial API spec: SAE 80W-90 GL-5. This product is available at any auto parts store and BRAND MAKES NO DIFFERENCE! Just make sure it says SAE 80W-90 GL-5. Check both side of the bottle. If your Muncie doesn't have a drain plug, you'll have to siphon out the old oil with some small, thin wall tubing. The capacity is approx. 2.5 pints.

[Jack H.]

Re: C-2 Muncie transmission oil recommendation

Wow….! This is good timing ….. I was going to ask the same question this morning. I'm planning to change the oil on the M21 for my 65' L76. The oil was last changed 36k miles ago in 1983. Aside from which oil to us, I will kindly ask the proper procedure, as I have never done this before. What type of tool do I use to extract the oil from the tranny..?

Thanks in advance ! David K

Simple siphon hose works okay, but you may want to consider investing in a suction gun which makes the job easier/quicker.

Pull on the handle and oil gets sucked into canister until full, then empty into recycling container by pushing on handle...rinse, lather, repeat until trans is empty.

The suction tool also makes putting fresh oil back in the transmission easier too.

Fill capacity according to specs which ends up being just under fill plug.

[Jack H.]

Re: C-2 Muncie transmission oil recommendation

Simple siphon hose works okay, but you may want to consider investing in a suction gun which makes the job easier/quicker.

Pull on the handle and oil gets sucked into canister until full, then empty into recycling container by pushing on handle...rinse, lather, repeat until trans is empty.

The suction tool also makes putting fresh oil back in the transmission easier too.

Fill capacity according to specs which ends up being just under fill plug.