Thinning of Transmission Fluid

Dale J. Swanson · Feb 7, 2013

The Transmission fluid in my l952 Ford 8N had a brownish color in it. I went to Tractor Supply and bought some All Mineral SAE 90 Ford Tractor Fluid. As I was pouring it in it appeared to me that it was very thick. It seems to me that you would have to run your tractor for quite awhile to let it warm up before you could begin to plow. I only put in 4 Gallons because I wanted to check with the experts on The Forum to see if it would be possible to thin this fluid out. Has anyone heard of using mineral spirits as a means of thinning it out? Will this thick fluid slow down the reaction time for raising & lowering my plow? I only use my tractor in the winter months when the temperature is below freezing. We are dealing with Lake Effect Snow at the moment here in Michigan. I would appreciate any help you can offer. Thanks

Dean · Feb 7, 2013

Ford originally specified 90W GL-1 "straight mineral oil" for the 9/2/8N tractors.

It is, indeed thick, when cold and you will need to operate the tractor for some time in cold weather before the hydraulic system responds normally.

CNH now specifies CNH 134D or equivalent, which is a much more modern oil and much less thick when cold. Use of 134D will result in much better cold weather performance.

Dean

POPGUN · Feb 7, 2013

I have ran a bushhog on 90 degree days for hours, pulled the dipstick touched the oil on it and well the oil was only 75 degrees. LOL,It takes more then I ever done to get the temp up so you would never get it in the winter.

Machine249 · Feb 7, 2013

I just checked out a jug of the Tractor supply universal hydraulic fluid I have here. It meets the Ford 134d specs so I would, and I have, just put that in there and forget about it.

wes(MI) · Feb 7, 2013

Dale, I live in Midland, 45 min west of the bay, and run 80/90 ep gear lube all year. Winter operation on fire up is disengage PTO, depress clutch start and run, then walk away for 10-15 mins. Go back, engage PTO and go away for another 10 mins. It'll still be slow for awhile after that, but not nearly what it could be.

TheOldHokie · Feb 8, 2013

(quoted from post at 22:06:30 02/07/13) The Transmission fluid in my l952 Ford 8N had a brownish color in it. I went to Tractor Supply and bought some All Mineral SAE 90 Ford Tractor Fluid. As I was pouring it in it appeared to me that it was very thick. It seems to me that you would have to run your tractor for quite awhile to let it warm up before you could begin to plow. I only put in 4 Gallons because I wanted to check with the experts on The Forum to see if it would be possible to thin this fluid out. Has anyone heard of using mineral spirits as a means of thinning it out? Will this thick fluid slow down the reaction time for raising & lowering my plow? I only use my tractor in the winter months when the temperature is below freezing. We are dealing with Lake Effect Snow at the moment here in Michigan. I would appreciate any help you can offer. Thanks

Mineral spirits is a great paint thinner but a horrible hydraulic or gear oil. Conventional SAE 90 GL-1 is about the lowest performing gear oil available and there are far better choices. To illustrate the differences here are the viscosity curves for 4 different gear lubes. The ideal operational viscosity for the gear oil in your tractor is somewhere in the 30-300 cSt range and the SAE 90 is 10 to 100 times that at a balmy 68F (20 C)!! Below freezing it barely flows and the hydraulic system simple cannot pump it. I would suggest you switch to a generic Universal Tractor Fluid (UTF) - the oil graphed in red. It is a generic version of the Ford 134D fluid the others have mentioned, inexpensive, and readily available at your local TSC, Walmart, or NAPA .

It will make starting easier and you won't have to let the tractor run for 1/2 an hour to warm up before you canuse it!!

TOH

tractorfix · Feb 8, 2013

Just remember that whatever leaks you have with the thick stuff will turn into torrents with 134d

Indiana Ken · Feb 8, 2013

Well you already paid for it and have 4 gallons in the tractor. You can't take it back and ask for a refund...I would pour another gallon in and see how it works.

Dad had a 1952 8N and he/we never changed the trans/hyd lube for the winter. I am sure that would have been 90wt year round, for Northern Indiana. When I bought my 1950 8N I used it the first winter before I changed out the trans/hyd lube. I suspect it had 90 wt in it and I had no problem in the winter, or did I have to allow it to warm up before using. When I changed out the lube I went to CNH 134D based on the dealer's recommendation and that has not given any problems.

Back in 1950 the 8N Operators Manual stated: SAE 90 wt for temperatures above 32 F and SAE 80 wt for temperatures below 32 F. But ask yourself how many farmers drained out 5 gallons of lube to replace it with something a little lighter. I think - very few - they had better things to do.

Jim in Eastern North Caro · Feb 8, 2013

Must be one those fancy refrigerated bush hogs that can cool the oil from 90 to 75!

rlpintx · Feb 8, 2013

A few oz of marvel mystery oil might help. Used it in a VW gear box with 90 w helped those mornings it got down into the low 30s.

souNdguy · Feb 8, 2013

the thick stuff is the oem oil it was designed for.

if you fdon't like the cold weather properties.. switch to a utf.

I'd do that before thinning it.. however.. the idea of thinning gear oil has been used before.

i have a JD-B manual that states to add a pint of kerosene to the gear oil for winter use..

POPGUN · Feb 8, 2013

No such thing, the gears are cooler cause their kept in the shade,snicker.

Thinning of Transmission Fluid

Dale J. Swanson

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Dean

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POPGUN

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Machine249

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wes(MI)

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TheOldHokie

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tractorfix

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Indiana Ken

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Jim in Eastern North Caro

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rlpintx

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souNdguy

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POPGUN

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