[JEFFMB]

Hi folks, getting ready to put in my 4 speed, it's been awhile since I've bought gear lube, whats the hot ticket nowdays for the old Muncie M20..
Thanks,
Jeff

[12run]

Good old 85W90 was always good enough for me.

[pdq67]

Ditto!

Dark teal colored stuff should smell a lot like good old EOS!!!

pdq67

[cortezsilver]

If you want to go synthetic use redline 75/90NS

[vince69]

royal purple, worth its weight in gold.

[JodysTransmissions]

Originally Posted by 12run

Good old 85W90 was always good enough for me.

Originally Posted by pdq67

Ditto!

Dark teal colored stuff should smell a lot like good old EOS!!!

pdq67

I also agree about the standard 85W90 lube.

As much as I like the newer fluids as stated, they will usually push out the front bearing retainer. After that, it will wind up getting on your clutch. Slip sliding away.

Some of the (an option) Autogear main drive gear/front bearing retainers use a lip seal. This will keep those light weight fluids from pushing out the front.

Regards, Jody

[ZZ430DropTop67RS]

Originally Posted by cortezsilver

If you want to go synthetic use redline 75/90NS

Ditto.

[MaxR]

I have a 5 gallon bucket of Royal Purple Max Gear 90. Will that work?

[Dave69Z]

I use valvoline 80-90w gl-5 with mt-1 spec per transmission manufacturers recomendation. It is a new autogear m-22w. Seems to work great in all temperatures.

[Straight-line-69]

Agree,..the chief engineer (George) at Autogear says NOT to use synthetics in his Muncies,..the synchros don't work as well. He recommends Valvoline 80-90 conventional gear lube with the MT-1 sub-spec (mentioned above) which is good for the yellow parts. Other lubes such as Castrol, don't have this sub-spec.

And it's no secret syns will leak before mineral lubes as mentioned above.

[RamJam]

I know this post is old but still hoping for help. I have a Muncie M-21. I want to make sure I put the right gear oil in it. I checked at advance Auto they have Valvoline 80-90 heavy duty for $4.88 a qt. Is this what I need? If not tell me what and where to get it and price. Wal-Mart has Rotella is that any good?

I already have a bad 2nd gear sync (It pops out sometimes). Mainly when I get off the gas. I don't want it to get any worse infact I'm hoping that changing the oil will make it a little better. Also how much do they hold? I've heard 1.5 and 2.5qts which is it?

Thanks

[77thor]

I prefer Valvoline, but it's just a personal preference....
Just be sure to get a brand name oil.

Anyone know what the fluid capacity of an M20 is??
How many quarts??

[68zproject]

I don't remember exactly but I think it's close to 40 ozs. And MacNeish said to never use synthetic.

[bilydean]

check this out at the Chevelle site. It talks about which oil to use and why.

http://www.chevelles.com/forums/showthread.php?t=132305

Dean

[67sprtcp]

I put valvoline in mine and it shifts flawless.