Fluids for my M54A2

[RenegadeActual]

What fluids would you guys recommend for my 5 ton? I am changing all 3 differentials, the transfer case, and the transmission fluids. What is recommended?

What types and what Viscosities?

LO 9-2320-211-12 Shows 80/90 for everything. But I know

 

[ericp351]

Your axles are very forgiving. Straight 90 wt. (Conv. type) hard to beat. 80 wt OK for all the hottest climates and highest loads. An 80W-90 Can't hurt. a 75w -140 or 80W-140 most likely OK, I doubt reqd. Lastly- artic service may like a 75W. Too thin to me unless truly artic. Leaks suck. 1 man's view only- but this is an application where you don't have to be a "brand-snob", just good, clean and dry gear oil. Ask 10 men, suspect a 1/2 dozen views...! Good luck.

 

[Wreckclues]

I flushed my transmission with diesel, ran through the gears with the transfer case in neutral, then refilled with a 90W GL1 gear oil.
Manual calls for an 80-90W GL1. Problem is no one on this continent makes it anymore. Our transmissions have yellow metal parts which aren't compatible with some synthetics. I've read other owners have used yellow metal compatible synthetics , but when I mixed an 80-90 GL4 with whatever was in my transmission I lost all power in everything but first and that would only creep.

 

[RenegadeActual]

https://www.napaonline.com/en/p/NHF65201

For the Trans?

Does the transfer case have yellow metal?

 

[Valley Rock]

when I mixed an 80-90 GL4 with whatever was in my transmission I lost all power in everything but first and that would only creep.

Huh ?

 

[Wreckclues]

Huh ?

It started out fine, ran through the gears OK, then when it warmed up I lost power in all but first. After flushing the transmission and filling with 90W GL1 everything was fine. Not sure what happened but I read somewhere that synthetics are designed for transmissions with filters, they entrain the sediments which are then filtered out. In our transmissions sediments settle out. When the GL4 mixed with the GL1 it must have stirred everything up and gummed the works.

 

[msgjd]

Does the transfer case have yellow metal?

yes

 

[RenegadeActual]

I bought NAPA GL1 90WT for the trans and transfer case.

Is all GL1 fluids safe for yellow metal? Or only certain ones?

 

[ericp351]

GL-4 is OK for "yellow metal" . Recommended for Mussel Car era gear boxes. Select vintage rear axles too. Some bottles marked "MT-90" or the like. Bit pricy, good load capacity. Chemically OK-confirm with bottle label. If member has trouble with it holding junk in suspension and causing troubled consider that also. Good luck. The troubles come with the "EP" (extra pressure??) additives in GL 5 to get it above GL 1 to 4. GL-1 most likely A OK as minimal additives.