85W-140 vs. SAE 90 gear oil

BigTone · Jun 2, 2012

Im changing all the fluids on my new (to me) Farmall m, the manuel calls for SAE 90 for the transmission but its very expensive and difficult to find, I was told i could use 85w-140 can anyone explain the difference and if its safe to use the 85x-140? I just do not want to do any damage....thanks for the help ~Anthony

rufus80 · Jun 2, 2012

85-140 is just going to be thicker it won't flow as well in cold temps. You can still buy an 85-90 at most farm stores and auto parts stores.

LJD · Jun 2, 2012

The viscosity isn't the issue. It's the additives and rating of GL-1, GL-4, or GL-5. The old SAE 90W was pure mineral oil with no EP (extreme pressure) additives - now called GL-1. Pretty much the same thing as non-detergent 40W motor oil. Tractor Supply sells it as "Ford 90W transmission oil."

85W-140 as well as modern EP 90W gear oil are usually rated GL-5 with the EP additives.

The only potential problems with using the modern EP oil is some older transmissions are two things: Plugging wet brake bands when they exist, and slight corrosion of yellow metals like brass and copper. Many GL-5 oils now adays are certified as "yellow metal safe" and it's not an issue. In regard to your Farmall M, I don't know if it has any yellow metal to worry about anyway. Certainly no wet brake bands. That's more of an issue in Case and Oliver Cletrac crawlers.

old · Jun 2, 2012

The 85W-140 is like the newer motor oils and act pretty much the same way as they do as in when cold it acts like a 85W oil and when hot a 140W oil so it helps some in theory that is. I use it in many of my tractors or I use the UTF type oil since it to is made for both the hyd and transmission and is a thinner oil

randy hall · Jun 3, 2012

i use straight 140 weight gear oil in our m tractors. these tractors are around seventy years old and have a lot of wear. and the 140 doesn't leak as easy. anytime that i have changed the rear end oil in an old m i would say that the oil that drains out is about 500 weight. the 140 that i put in is thinner than the old oil.

guido · Jun 3, 2012

Hello Big Tone,
I would not put in any oil that has a higer viscosity. 90W is what is calling for, as someone
already suggested 75w90 would be O.K. to use.
Guido.

DanR · Jun 4, 2012

Either one will work fine in an M. It's the 13 gallons that's a killer.

Texasmark1 · Jun 4, 2012

I go to the local "good old boy" auto parts store that also has a good access to Tisco parts for my tractors, to get my 90W GL-1, in the 5 gallon pail for a very reasonable price. I also have a 2 gallon container of the other which I got at ww which I used in the gearboxes of my older shredders as the lower seal usually leaked somewhat and I didn't feel like changing it.

I agree with LJD's comments. Been running this farm for over 30 years and first tractor was Farmall B.

Mark

mkirsch · Jun 4, 2012

It's a Farmall M. All you're doing is lubricating some loose-tolerance gears and bearings, which are plenty worn at this point in the tractor's life.

There are no pumps, no wet clutches, no wet brakes, nothing fancy back there... Just a simple old tractor.

Just buy whatever "gear lube" is available and cheapest. I'm surprised straight 90 is so difficult to find and so expensive...

85W-140 vs. SAE 90 gear oil

BigTone

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rufus80

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LJD

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old

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randy hall

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guido

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DanR

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Texasmark1

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mkirsch

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