Mower gear oil

[KubotaOne]

I posted this in the Kubota room, probably should have posted this question in this room. So, here's my question.

I have the 60" MMM on my B-3030. The mower owners manual calls for SAE90 when I change the gear oil. My dealer says they only use UDT hydro fluid, and they don't even carry SAE90. He said UDT is better, particularly in our colder climate (Toronto)

Is it alright to use Super UDT fluid?

thanks

[jeffmazz]

I use 75W90 synthetic (Mobil 1) gear oil in my mmm gearbox. My dealer recommended this and after over 120 hrs. of cutting I haven't had any problems. I think the UDT is too thin for the gearbox even in cooler climates. I wouldn't use it.

I have used synthetic gear oils for many years in the differentials of off road race vehicles with zero oil related failures. Race day temps can be anywhere from sub-zero to +100 depending on the time of year and location.

75W90 synthetic flows well at cooler temps. If you don't cut your grass in -20 degree temps you will be fine.

Jeff

[Soundguy]

While I don't mind running UTF type oils in tractor gearboxes that spec them.. I wouldn't want to in a little mower gearbox. Usually on the tractor.. the sump is large.. like 5 gals.. or has an oil cooler.. etc. On that little mower gear box.. what does it hold? a quart or less? I'd be afraid of it being to thin.. I think I'd go with what the mower recomends.. 90w... or for a mower with no rec's.. something like 85/140

Soundguy

[KubotaOne]

thanks Soundguy, I've read alot of your posts over the last year and value your advice. The gearbox holds less than half a quart. Looks like I'll stick with a dedicated gear oil, as per the manual. I did however find this response from a Google search I did. You might find it interesting, of course I'm not sure how credible the author is.


Specified oils are as follows: for most temperature ranges use 10w-30 engine oil with the most current diesel rating (CG, CH, etc)/ for the transmission and final drives use Kubota UDT or Super UDT. Heavy gear oil, 80w90 is also approved for the rear axles instead of UDT but we always install UDT. Mower gearbox calls for straight weight SAE 90 gear oil, but over the years we have best performance with lower heat build-up using Kubota UDT in the gearboxes. This applies to front axles in Kubota tractors with front wheel assist.

My recommendation to all our customers is to stock and use only two oils for their tractors; any good name-brand diesel rated oil with viscosity according to temperature, use, and owner's manual AND either Kubota UDT or Super UDT depending on use, temperature, thickness of wallet (since Super UDT is more expensive)

One final suggestion on the subject of grease for mower spindles - spend a little more and get hi-temp grease rather than chassis grease. It will hold up much better and stay where you want it, AND don't over grease. Every three or four mowings works for us. Greasing the spindles every time you mow tends to over fill and then attract dirt, debris, etc and can lead to premature bearing failure. Even the factory sealed bearings on a T-series mower are warranted under normal intended use for the machine for 2 years.

[Soundguy]

It's common for some manufacturers to spec a UTF type oil in everything but the crankcase. For example.. my ex-Nh1920.. specced utf in the power steering, front axle and final drives, and the hyds/tranny/diffy common sump area, and engine oil inthe crankcase. Same for units without common sumps in most situations.. UTF in all.. engine oil in crankcase.

My cynical 'guess' for this is that it's easier for the dealer to stock less products.. However.. According to the specs.. the UTF stuff is designed for final drives / .. etc. I never had metal show up in the oil, or on the magnetic drain plug ont he common sump.. it was a gear unit.. so the tranny got a workout.. the UTF must be good stuff.. or so many applications would not spec it.. must have a superb addative package... Being a bit old fashioned.. I generally run a true gear oil in my non-common sump gearboxes

Just as a note.. it's also possible to find machines that spec engine type oil in trannies and in rare instances.. gearboxes. Lots of heavy equipment specs 30 and 40w oil for trannies.. and have seen units that spec 50w engine oil in gearboxes... as well as some applications that use a 0# pourable grease like JD cornhead lube, for some gearbox applications, as well as plain old grease in some gearboxes.. etc.

Soundguy

[KubotaOne]

Thanks for your responses guys - still haven't changed the gear oil yet.

I was at another Kubota dealer last week and I asked what they used in mower gear boxes. He said "a good quality SAE 80w90 oil, GL5 spec"

I already have two kinds of that (not being cheap, but would save me another trip to the dealer if I can use what I've got) One is Hew Holland Ambra Hypoide 90 Gear Lube SAE 80w-90 GL5, the other is Castrol Hypoy C SAE 80w-90 GL5.

Can I use either of these?

[jeffmazz]

Either oil will be fine.

[5030]

Interestingly, I use UDT in my Kubota but in the summer in the front axle I always switch to 85-90 Spirax.

I agree with the others, API GL5 would be better in that little gearbox than UDT from a heat conducting standpoint.