Kubota front axle, hydraulic fluid or gear oil?

[Jay4200]

The fact that 80-90 is heavier, is a very popular misconception. The 80-90w suggests it's heavier. It's not. Gear oil is not tested on the same scale as motor oil.

Do some research, and some pour tests, and you will see it for yourself. The differences are not substantial.

The actual viscosity, between 80-90w gear oil and hydraulic transmission oil, at room temp. is basically the same.

Both are light weight gear oil, which is why they are interchangeable in this application.

80-90w gear oil, hydraulic transmission oil, and 30w motor oil are all similar in viscosity. With much of the differences being that viscosity's do vary. Any two 30w motor oils for example, will have different viscosity's.

An EP gear oil, offers the highest degree of protection for hypoid gears. (The kind in a diff.). So, it would be best by that standard, if you have the option.

Is it necessary? Probably not. But, if it's only 2 quarts. And, someone wants to go all in, it's a good option.

If someone is worried about cold weather operation, there is such a thing as synthetic gear oil, for a couple of bucks more. Win, win.

Actually, gear oil IS thicker. UDT viscosity is roughly equivalent to 15wt motor oil (SUDT is 10wt) and 80W90 is roughly equivalent to 30wt motor oil. Just sayin'.

JFTR, I use 90W140 in my L4200's front axle because one of my bevel seals leaks like a sieve.

 

[ray66v]

Actually, gear oil IS thicker. UDT viscosity is roughly equivalent to 15wt motor oil (SUDT is 10wt) and 80W90 is roughly equivalent to 30wt motor oil. Just sayin'.

Kubota SUDT has a published viscosity of 37 at 40c. That is equivalent to a 20w oil at 104F.

Some oils are thicker, some are thinner. Even in the same grade.

If you read what I posted, I was debunking the belief that the gear oil is substantially heavier.

I said, at room temp, they are basically the same.

Not interested in splitting hairs.

If you do a timed pour test, at room temp, and compare them, you will see they are basically the same.

 

[Fallon]

I picked up some EP 80w 90 by the way. Have yet to drain & refill the axle. It was only a couple bucks extra for the 2 gal jug of EP over the basic 80/90, so I figured it couldn't hurt. Cheaper than my SUDT by a decent bit.

 

[oldpilgrim]

i don't have a kubota but i put the same stuff in my front axle as i do my hydro. One less type of lubrication to have around.

 

[ovrszd]

The fact that 80-90 is heavier, is a very popular misconception. The 80-90w suggests it's heavier. It's not. Gear oil is not tested on the same scale as motor oil.

Do some research, and some pour tests, and you will see it for yourself. The differences are not substantial.

The actual viscosity, between 80-90w gear oil and hydraulic transmission oil, at room temp. is basically the same.

Both are light weight gear oil, which is why they are interchangeable in this application.

80-90w gear oil, hydraulic transmission oil, and 30w motor oil are all similar in viscosity. With much of the differences being that viscosity's do vary. Any two 30w motor oils for example, will have different viscosity's.

An EP gear oil, offers the highest degree of protection for hypoid gears. (The kind in a diff.). So, it would be best by that standard, if you have the option.

Is it necessary? Probably not. But, if it's only 2 quarts. And, someone wants to go all in, it's a good option.

If someone is worried about cold weather operation, there is such a thing as synthetic gear oil, for a couple of bucks more. Win, win.

Good stuff right here!!!! I actually conducted my own pour test a few years ago. Bingo. 80-90w and UDT are basically the same viscosity. Only difference is additives. Since I don't see anything in the front axle assembly that needs special additives, I use 80-90w.

 

[AlanKent]

I get it that Kubota recommends either UDT or gear oil, but can I top off the fluid with either one? Not sure what's in the tractor now (from the factory).

 

[CalG]

The hydraulic fluid is thinner and might be a plus in your colder temperatures. When and if the hubs start leaking then I tell people to use the gear oil till they have to be resealed.

Except ...I have read......

UTTO Prolongs seal life over gear oil.

So if you don't need the EP properties of sulfur, Go UTTO!

I use it in EVERYTHING that isn't Infernal Cornbustion!

Think about it, what is there in a front axle that isn't in the big box under the seat?
If UTTO can work in one, it should work in both.
Are there ANY tractors that use a hypoid front diff? I've never heard of one.

 

[CalG]

I get it that Kubota recommends either UDT or gear oil, but can I top off the fluid with either one? Not sure what's in the tractor now (from the factory).

They mix just fine!

 

[CalG]

Actually, gear oil IS thicker. UDT viscosity is roughly equivalent to 15wt motor oil (SUDT is 10wt) and 80W90 is roughly equivalent to 30wt motor oil. Just sayin'.

JFTR, I use 90W140 in my L4200's front axle because one of my bevel seals leaks like a sieve.

Check that seal for debris. Grass and what not. I had a leaker on the Hurlimann front axle, and a good cleaning (long grass) took care of it!

 

[DarkBlack]

UTTO Prolongs seal life over gear oil.

So if you don't need the EP properties of sulfur, Go UTTO!

Where did you read this?
Can you post a link to it , please?
The particular elastomer composition would have to be discussed, to start.
I’d love to see an actual technical study that compared a gearbox lubricated with good gear oil against a gearbox lubricated with UTTO, where they found the seals leak sooner with gear oil, than with with UTTO.