SUDT

SkyPup · Apr 19, 2006

SUDT is specifically for use in their modern (made in the last 5-6 years) HST and GST transmissions and hydraulic systems.

If yours is older than that, use UDT, unless you are in Alaska or Canada, then use SUDT for the improved low temp performance.

MessickFarmEqu · Apr 19, 2006

( Plus, I'm pretty sure they come with UDT in them. )

Everything ships with Super UDT.

Marooned · Apr 19, 2006

Another Question (while we're on the subject):

If SUDT is not synthetic, would a synthetic hydraulic oil that meets Kubota's specs be better than the SUDT? /forums/images/graemlins/confused.gif

I was considering going with full synthetic? (Such as Amsoil or somthing similar.)

newcountry · Apr 19, 2006

( But this question remains: if sudt is always better in every way, that means udt is always inferior in every way. Why would Kubota, any dealer or any owner ever make it, stock it, sell it, or use it?)

Kubota probably makes it for the same reason Wal-mart sells engine oil for 89cents a quart - because someone will buy it. I think I know what you're getting at - If Kubota really felt so strongly about SUDT they wouldn't even offer UDT. I say, this is capitalism at it's greatest. I would always rather have more choices for me to choose than have companies make those decisions for me.

( Plus, I'm pretty sure they come with UDT in them. )

What?? That's pretty conspiratorial. /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif

SkyPup · Apr 19, 2006

Amsoil's Full Synthetic Hydraulic fluid is excellent, as is Chevron's and PetroCanada's.

N80 · Apr 19, 2006

( Everything ships with Super UDT. )

Well, that makes a little more sense to me. (My dealer suggested otherwise but I trust what you're telling me). And, if it comes with SUDT in it, then that's what I'm going to put back in it.

My B-I-L farmer uses the synthetic Amsoil in all his eight large tractors. How does its cost compare to SUDT? How do its advantages compare with SUDT? You don't have to change synthetic motor oil as often, is this true with tranny/hydro fluid? I can't imagine going more than 400 hours before changing it, but if it is truly safe to go 500 or 600 and synthetic might really be worth it.

So many choices, so little knowledge (on my part.)

Spiffy · Apr 19, 2006

We had a similar discusion on the PT forum recently, discussing single vs. multi vs. specialty vs. synthetic......

I'm fairly convinced, things like SSLs or PTs etc, cause temp rises even nastier than a hydro tractor; so the parrallel is indirect but interesting.

Anyways, the multis will maintain a tighter viscosity, however, often at the expense of foaming and shear abilities (these do apply more to motor oils [often having high detergent rates too] used as hydro oils than the specialty oils like SUDT). It seemed to follow that if you have high ambient temps (Florida, Texas, etc) the single viscosity would be great, but the data I looked at would imply the need for ISO100 rather than ISO68.

To deal with temp swings [on paper anyway] the synthetics showed the best combinations of stable shear and viscosities, while the multi-viscosity dinos definitely held viscosity better than singles [and should by definition].

Sooooooo? For the questions here: If you like synthetics, do that. If you like your 'bota dealer or have a good source for 'bota products I'd run whatever you think it came with [unless temps dictate Super]. If you like your Deere or NH deeler better, the specs on Deere and HyTran oils looked pretty good (though the info on SUDT and UDT is so vague, it's hard to tell which actually compares better to other oils - for that reason, maybe everyone should boycott (S)UDT until Kubota publishes some specs /forums/images/graemlins/tongue.gif ). Judging from the fact one user in this thread noticed subpar performance with Deere, I have to wonder if the SUDT isn't a higher viscosity than Deere or the mechanic took the Deere oil from the wrong barrel.

SkyPup · Apr 19, 2006

The synthetic is much more resisitant to heat and subsequent oxidation and shear, which is why I use it.

My 55 galon drum of Amsoil's Synthetic Hydraulic fluid cost me about $850 delivered, which was much cheaper than I could acquire the SUDT for....... /forums/images/graemlins/wink.gif

N80 · Apr 19, 2006

Hmmm, my tractor holds 11 gallons. It will need to be changed every 400 hours which for me will likely be about every 6 years. A 55 gallon barrel would provide 5 changes, five changes x 6years equals 30 years! If I'm alive then I'll be beating the average male lifespan.

Seriously though, the improved heat resistance does appeal to me. It is frequently (usuallly) 90+ around here in the summer when my tractor will be used most. Time for more research. I could probably just go in with my B-I-L for a barrel or something a little smaller. He may get some sort of bulk discount too.

SkagitStan · Apr 19, 2006

I'm confused. If I read the chart correctly, after 30 minutes, the available flow rate is almost identical between the 2 oils. What, other than temperature, causes the flow rates to converge?

If temperature is the only variable, then I'd think the graph should indicate the starting (or ambient) temperature, and oil temp required to reach the 30 minute flow rate.

If the chart is based on ambient of -10F, then it isn't particularly relevent to my climate. If it's based on 30F, then maybe it is useful in my climate.

If available flow rate at low temp is the main advantage of SUDT (which is what my dealer tells me) (Are they right?) then what's important to me is how long the oil takes to get to safe operating temp in my normally mild western WA. climate.

If there are other important differences, please tell me what they are! My tractor may be $15K, and I sure don't want to trash it. BUT, my tractor is $15K, which leaves that much less for unnecessary luxuries like spending on oil that isn't shown to improve its health or life. /forums/images/graemlins/confused.gif