Oil viscosity

Stephen Newell · Feb 17, 2018

Is there a simple way to test the viscosity of gear oil. I have an issue with my tractor which is leaking hydraulic fluid into the transmission which has gear oil. I know it's bound to be diluting the gear oil and I don't want to add ruining the transmission to it's problems. It's not possible at this time to repair the problem, I just need to know how to monitor the viscosity of the gear oil.

Greg1959 · Feb 17, 2018

In the lab, we measured viscosity at 40C and 100C. I too, am curious if there is another way????

Andy Martin · Feb 17, 2018

You can buy a paint viscometer very cheaply. Fill it with new gear oil and measure the time to fall to a set line part way down the cup. Don't try to go to empty. Use that measurement as a base to compare against your suspect gear oil. Do all the measurements in the kitchen at 70F. Actual viscosity varies greatly with temperature so use the same temperature every time. You won't calculate the API viscosity this way but you can determine whether your gear oil has thinned.

But what kind of tractor? It may run fine with hydraulic fluid in the gearbox (like HyTran in an M). If it's an old tractor the old gear oil it was designed for may not be as good as the new hydraulic fluid.

JD Seller · Feb 17, 2018

You did not say what tractor your having the issue with. Many old tractors run better with hydraulic oil rather than the original gear oil in the transmission.

I have an Oliver 1655 the transmission came with gear oil in it. I had the needle bearings on the input shaft seize twice during cold weather use. A local Oliver mechanic told me to put Hygard or Hytran in the transmission. That has been over 20 year ago. Never any trouble after that.

Janicholson · Feb 17, 2018

Not to worry. Hydraulic oil mixing will not likely hurt anything. Especially if it is Hydraulic Transmission (tractor Fluid) type. Just keep it drained to the level plug or Full mark to avoid leakage. Fix it when you can. Jim

Bob · Feb 17, 2018

Stephen, MANY tractors, including very high HP tractors run "hydraulic oil" in the transmission, differential, and final drives.

Dunno what tractor you are playing with, or exactly what's going on, but (IMHO) you are tilting at windmills by thinking you need to measure/monitor/stress over the viscosity of it's "gear oil".

Curious as to why you think you need to???

Stephen Newell · Feb 18, 2018

This is a Case 210B which the transmission is suppose to be operated with gear oil. At the top of the transmission it has a hydraulic mechanism which operates the three point hitch. This unit is leaking hydraulic oil into the transmission and leaking out the seals where the brakes are. Sometimes sitting overnight it might leak as much as a quart of hydraulic fluid there. I have put a pan under it before and can tell it's way thinner than gear oil so I know what it is.

Even if I had the time to work on the tractor I'm told there was three different mechanisms for the three point hitch. I would have to break it down and then find someone which could determine which parts would be needed and then mail order the parts. The tractor would probably be down three or four weeks.

Stephen Newell · Feb 18, 2018

The fluid I'm using is 303. I thought the same thing about the fluid mixing into the gear oil but then I got some information that hydraulic oil mixing with gear oil will thin it to the point where it will wear the gears out.

JDEM · Feb 18, 2018

90 weight "gear oil" is the same as 30-40 weight motor oil.

"Hydraulic oil" is usually the same as 20 weight motor oil unless it is special cold-weather grade.

Just pour a few drops and compare.

Stephen Newell · Feb 18, 2018

OK, that sounds reasonable. I don't have a viscometer but will get one soon.

The tractor is a 1959 Case 210B. I know the transmission would work alright on the 303 hydraulic fluid. What I'm worried about is the thinner oil prematurely wearing the gears out. I think if thinner oil was good they might have originally recommended 10w oil instead of 90w gear oil. Not being sure I'm inclined to stick to manufacturer specifications.

Texasmark1 · Feb 18, 2018

Is it a Ford, 1960's era? I had the same problem with my '63 2000D and Sound Guy put me onto the fact that my hydraulic tubes, that run through the tranny sump, get pin holes in them which allow the high pressure hyd fluid to enter the tranny case.

One day I decided it was time to change the tranny and the hyd sump fluid so I just did both with JD303 trans/hyd fluid oil from wallyworld...I find 303 and 134 specks co exist on most containers so I use either spec as a reference.

Result is a little noiser tranny but shifting is improved, especially durning the winter months. Every once in awhile I pull the fill plug on the side of the tranny case and let the excess out and refill the hyd. sump if need be. Not all that much but does require attention from time to time.

buickanddeere · Feb 18, 2018

(quoted from post at 10:52:52 02/18/18) OK, that sounds reasonable. I don't have a viscometer but will get one soon.

The tractor is a 1959 Case 210B. I know the transmission would work alright on the 303 hydraulic fluid. What I'm worried about is the thinner oil prematurely wearing the gears out. I think if thinner oil was good they might have originally recommended 10w oil instead of 90w gear oil. Not being sure I'm inclined to stick to manufacturer specifications.

Not to worry . Those transmission gears running in Hy- Gard will outlast all of us here .

ss55 · Feb 18, 2018

It would help to know what the tractor is. A good hydraulic/transmission fluid should work fine in most 1960's and newer tractors, probably most 1950's tractors too. The hydraulic capacity of most older tractors with separate hydraulic systems is small compared to the transmission capacity, it will take a lot of leaking to dilute the transmission oil. If you are not sure what is in the transmission, it might be a good time to change the transmission oil, maybe switch to a good hydraulic/transmission fluid.

M-MAN · Feb 18, 2018

Both are wet and slick so worst case is you will develop more leaks.

Stephen Newell · Feb 18, 2018

The tractor is a 1959 Case 210B. It's a separate system but the hydraulic device is on the top of the transmission much like the lid of a box. It's developed a leak letting hydraulic fluid into the transmission. The hydraulic fluid is too thin for the seals around the rear axle. I changed those a few years ago and it's leaking fluid out on the brakes so right now I have little to no means of stopping the tractor. I thin the seals would hold back gear oil.

SVcummins · Feb 18, 2018

Wrong hydraulic oil is not ran in transmissions . tractor hydraulic fluid is not the same as hydraulic oil

JD Seller · Feb 18, 2018

You need to drain the transmission fluid level down so it is not running out your seals. The Hytran/Hyguard fluid is not just hydraulic oil. It is made for carrying heavy gear loads. I can guarantee that a 250 hp modern tractor, is going to put more load on the gears than your Case 210 will ever do. Also are you running the tractor hundreds of hours a year??? If it is like most weekend user tractors it will not get a 100 hours use a year. So wear would not be an issue.

IF it where mine I would fix the leak but would more than likely keep the Hytran/Hyguard in the transmission. It flows much better than gear oil. It also has moisture inhibitors that gear oils do not have. There are reason that most modern tractors use little if any gear oil.

sammydwm · Feb 19, 2018

When I was an engineman in the Navy we used a falling ball viscometer when the oil sample had cooled off to same temp as the the control sample.

SVcummins · Feb 19, 2018

Hygard and I'm sure hytran is as well a gl5 rated oil

buickanddeere · Feb 19, 2018

Gear oil into a wet brake or wet clutch system will ruin the friction material.

Oil viscosity

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