Hydraulic Fluid for a tired Kubota B7200 with HST

[CJN8]

So i picked up a super cool Kubota B7200 with a FEL and rear rollover box blade to help around our little ranch house in San Diego CA. The little dude runs great but I can tell the HST is getting a little tired. Once it gets up to temp if you are really working it the HST whines and loses some of its "push power" if you are working a full bucket or moving some dirt. I have changed all the fluids including the motor, transmission/hydraulics (common sump) and replaced all the filters and cleaned the hydraulic screens (both). When the fluid is cold (right at start up) it has great push power and does not whine if I am working her. When I changed the fluid I used Super Tech Hydraulic fluid I bought from Walmart which is Kubota UDT compatible per their spec. My question is, is there an additive or other brand of fluid that is thicker or better maintains its flow properties? A new HST transmission runs about 2200 dollars and if I can get by with just going to a thicker hydraulic fluid I would like to do that for the time being. Thoughts?

Nate

 

[jbbwv]

Change the fluid to the Kubota Super UDT and be happy. It's a bit more $$ than the regular UDT, but well worth the time and money.

Ask me how I know

 

[Rand]

try oem fluid.. alot of that meets or exceeds stuff isnt really meeting or exceeding.. ( at least in the tractor world)

 

[Donald]

Originally Posted By: jbbwv
Change the fluid to the Kubota Super UDT and be happy. It's a bit more $$ than the regular UDT, but well worth the time and money.

Ask me how I know


+1 A Kubota tractor is an expensive machine. It will hold its value well. Don't skimp on the fluid.

 

[CJN8]

Thanks for the input. I did some additional research last night and it seems others had issues with the less expensive brands too. Majority agreed that if your tractor is a hydrostat use the UDT or SUDT. I guess it probably maintains its viscosity better than the Walmart brand. I also read the ISO rating of UDT was closer to 68. Still trying to figure out the ISO rating of the Super Tech I purchased at Walmart.

Thanks,
Nate

 

[IndyIan]

I think the main number you are looking in a fluid is Kinematic viscosity at 100C in your case.
Being in San Diego you don't have to worry about cold flow I assume so you maybe able to go with some cheaper stuff that has high viscosity all the time.
Highest I've found is 10 cSt in petrocanada duratran synthetic, Kubota SUDT is 8.1, and many brand names tractor fluids are in the 9.5 range.
I don't know how hot your fluid gets so perhaps the higher viscosity index of SUDT comes into play? Duratran has a higher VI of 212 anyways vs 199 for SUDT.
Kubota also doesn't publish specs on their UDT on their website, so I suspect its not impressive but may have a higher viscosity at 100C anyways? For the price of the Kubota stuff you can get some Chevron 1000 thf that has good specs that are published, 9.5 cst at 100C.
I assume you've checked the hyd fluid cooling system? Some just have a fan that often gets damaged.