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DRankin
Join Date: Jan 2000
Posts: 5116 Northern Nevada
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2004-06-15          88600

I have been studying the viscosity numbers and comments on this board.

Some folks have reported their HST's are sluggish in the stop and start phases. Dealers have told some that use of UDT in their HST equipped Kubota's instead of Super UDT (which has a very thin viscosity) will result in poor transmission performance.

Deere pushes very hard for us to use Low-Vis despite temp charts that seem to indicate otherwise.

From my own experience, I bought a BX22 that had Super UDT installed at the dealer. It worked just fine. At the 50 hour mark I changed to Chevron All Weather... which, although it is a full synthetic has a higher viscosity than Super UDT.

Two things happened after the change. The tractor started to "creep" and I noticed that the top speed felt slower.

Recently, I bought a Kubota RTV from a local dealer who does not carry any Kubota fluids. I took delivery of the RTV with Case fluids in the sump. All was well at first, but now I notice at the 30 hour mark that the transmission is starting to act a little sluggish. When I take my foot off the pedal there is a one second or so delay before the pedal retracts and I feel the HST brake. I get same delay when I start. I suspect that at 30 hours, the fluids have started to change viscosity due to normal wear.

So..... here is the question I pose: Maybe hydrostatic transmissions are designed/machined to function best with thinner viscosity oils.

We wouldn't consider pouring gear lube in the automatic transmissions in our cars even though we know that it is the fluid of choice in a manual transmission.

We also know that pouring automotive 10w-30 in an aircraft engine instead of the straight 90 wt will ruin it.

Is it possible that UDT and Hy-Gard are best used in manual transmissions while Super UDT and Low-Vis are designed to function best in HST's?

Maybe the clearances in an HST are too close for the higher viscosity fluids.


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kwschumm
Join Date: Feb 2003
Posts: 5764 NW Oregon
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2004-06-15          88601

Is Deere pushing us to use low vis HyGard in our hydros? The guys at Fisher Implement told me they use regular HyGard in nearly all their HST machines. I haven't noticed any creeping or sluggishness in my eHydro, before or after the 50 hour service, and it uses regular HyGard. Maybe the sluggishness is there and I'm just used to it, but it certainly doesn't creep. I can see how maybe the low vis stuff might operate a little snappier, but I worry about the behavior when it gets really hot on a hot day.

We need some anecdotal evidence from guys who switch from regular to the low-vis stuff to see if it operates better under varying operating temperatures. ....

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DRankin
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2004-06-15          88609

Fisher got my 4115 on a transfer from another dealer and it was already prepped so I don't really know what it had in it when I bought it.

The Fisher parts guys there said that Low-Vis was the proper fluid and told me they didn't recommend Hy-Gard for my tractor.

The local dealer used stronger terms. They said Hy-Gard will not stand up to the stresses of an HST and does not have the anti-foaming properties of Low-Vis and will not protect the transmissions properly.


....

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kwschumm
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2004-06-15          88610

Man, this is frustrating! If the manual calls for Hy-Gard in most areas of the country, and it is not the proper fluid for the transmission it seems there would be a fair number of reports of failing transmissions. That doesn't seem to be the case.

Maybe we need to circulate a petition and send it to JD to get a definitive answer. ....

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kwschumm
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2004-06-15          88613

I'm curious. If the HST fluid foamed would you see it in the site glass? I've got some bush hogging to do tomorrow and it will be a hot day so it's something to keep an eye on. ....

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Chief
Join Date: Jul 2003
Posts: 4297 Southwest MiddleTennessee
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2004-06-15          88617

I just remembered after reading this post that I got in the Product Data Sheets for Kubota UDT oils day before yesterday if you have an questions. There was another post that Mark and Ken asked me a question about UDT but my CRS is acting up again today. ;o) ....

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DRankin
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2004-06-15          88647


Yes, please, these numbers if they provided them:



Viscosity at 40°C (cSt)
Viscosity at 100°C (cSt)
Viscosity index ....

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Chief
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2004-06-16          88668

Kubota UDT
Code 3501
SAE Grade 10W-20
API Gravity at 60 deg. F 28.8

Viscosities
-18 deg. C,cP 2150
100 deg. C,cSt 9.36
40 deg. C,cSt 59.33
210 deg. F,cSt (SUS) 9.65 (58.0)
100 deg. F,cSt (SUS) 65.92 (306)

Viscosity Index 140
Flash Point, C.O.C., deg. F (deg C) 390 (199)
Pour Point, deg. F (deg. C) -33 (-36)
Color, ASTM D-1500 3.0




Kubota Super UDT

Specific Gravity at -15.6 deg. C 0.877
Viscosity at 25 deg. C, cSt 84.00
Viscosity at 100 deg. C, cSt 9.00
Viscosity at 40 deg. C, cSt 45.0
Viscosity Index 192
Pour Point deg. C max -46
Zinc, wt. % 0.17


Super UDT Part #'s

70000-40100 12/1 quart
70000-40101 4/1 gallon
70000-40102 2/2.5 gallon
70000-40105 5 gallon Pail
70000-40155 55 gallon drum

I'm all spec'd out now Mark. ;o) Thought I would throw in the part#'s if anyone was interested. Hope this covers all the bases.
....

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DRankin
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2004-06-16          88670

Thanks Randy. ....

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Chief
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2004-06-16          88671

Glad to help out Mark. Indeed welcome! ....

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DRankin
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2004-06-16          88674

Interesting.

Super UDT is a virtual twin to Chevron All Weather. ....

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Chief
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2004-06-16          88675

It wouldn't surprise me if Chevron makes Super UDT for Valvoline who sells it to Kubota. Or at least Chevron makes All Weather THF to compete as a direct replacement for Super UDT. I have been using John Deere Hyguard but I make give the AWTHF a whirl at the next trans. fluid change out. I wonder if they make a green tinted fluid for that???? ;o) ....

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DRankin
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2004-06-16          88678

Maybe on St. Paddy's Day..... ....

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