Kubota front axle, hydraulic fluid or gear oil?

[Fallon]

From the Kubota manual...
Front axle case 4.5 L, 4.8 U.S.qts., 3.9 Imp.qts. KUBOTA UDT or SUPER UDT fluid* or SAE80, 90 gear oil

Would you put in hydraulic fluid (UDT or Super UDT) or some 80W-90 gear oil? Going to change out the front axle fluid & thinking I'll just pick up some 80w-90 tomorow, but wondering if anybody had any opinions as they are both recommended by Kubota.

 

[dragoneggs]

There has been lots of chatter here in the forums but I think the real answer is that it doesn't matter... at least to Kubota!

 

[art]

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.

 

[teg]

I use gear oil but wouldn't hesitate to use hydraulic fluid... There was a time... way back, where kubota's front axles were "low" on front axle oil from the dealer.

I personally think if you use gear oil, you need to check the level again (and again) since it seems to take it's time to seep into all the nooks and crannies....

 

[ray66v]

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.

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.

 

[Coyote machine]

FWIW, Kioti specs the same thing: either. I use the hydraulic, UTF because it's handy to not have to stock yet another oil for my numerous machines. Synthetic might be best for seal longevity, but any high quality lube, changed when required, should do fine.

 

[High Compression]

I was told by my Kubota Dealer Service manager to use 80-90W gear oil. Especially if you have a FEL.

 

[Texasmark]

I don't think viscosity change at temp extremes is a big deal on a 4wd front axle like it would be in a transmission where you are trying to shift manually or a hydro trying to pump fluid. What would matter to me is the ability of the lube to remain between 2 surfaces under pressure.....don't remember the name for that test but that's what keeps gears from wearing....a lubricating layer between steel surfaces.....not a petroleum engineer. I have been a heavy oil guy all my life until I bought a 2007 Dodge 1500 4.9 (or 4.7...one's Chevy the other Dodge) and they insisted I use 5w-30. Sad the oil pump was made for light oil and the pressure did stay up when hot like I used to get with heavy viscosity oil in my prevous 318 and 360. Then comes the '09 with a hemi and it emphatically stated 5w-20 and made the same comment about the oil pump. It was also a 8/4 engine and the manual said the conversion can malfunction with thicker oil. Had no problems with reliability, oil burning, nor low oil pressure with the thin oils....used Mobil 1.

I use Premium Universal Trans/diff/wet brake/hydro oil in my main sump on my Branson and also in the front axle sump per the mfgr recommendation. Takes about 2.5 gallons there and about 10 in the rear so I buy one oil and it does both jobs. Can't complain. I even started using light oil in my 1960 vintage Fords and have smoother shifting, much easier in winter, no noticeable increase in leakage and since the main sump uses JD 303/Ford 134A now my trannies doe too. These tractors don't have wet brakes and hydros and don't need the Premium and I save a few bucks. Now you know what I know for what it's worth.

 

[5030]

I farm and I work both my Kubota's probably harder than I bet 95% of the posters on this site and both have front loaders and I use both to near capacity in the field, moving and loading big rounds, That isn't on smooth ground either, that is traversing fields loaded (with one round on the back as a counter balance... been doing that for a number of years now (maybe 5) with no issues on the front axle, no leaks, no seal issues.

I started out on my first fluid change with SUDT (15 gallons in the transmission cases and about a gallon in each of the front axles). I maintain a frequent grease regimen.... no issues. Second and subsequent changes are with Chevron All Weather Synthetic Hydraulic fluid. Still no issues or seal leaks out front... I use 'em hard.

 

[fortec]

From the Kubota manual...
Front axle case 4.5 L, 4.8 U.S.qts., 3.9 Imp.qts. KUBOTA UDT or SUPER UDT fluid* or SAE80, 90 gear oil

Would you put in hydraulic fluid (UDT or Super UDT) or some 80W-90 gear oil? Going to change out the front axle fluid & thinking I'll just pick up some 80w-90 tomorow, but wondering if anybody had any opinions as they are both recommended by Kubota.

You can find UTFs approved for use in Kubota axles.