Oil & Fuel Which type synthetic hydraulic oil for Kubota 3400 HST

Rice Rider · Dec 7, 2011

I am comming up on my 500 hour service and will need new hydraulic oil. I bought the tractor from a truck driver who replaced all oils with full synthetics. On the Amsoil web page, I have left a question regarding which type ISO is compatable with my machine and have yet to get an answer. I have also heard that one should not go back to petrol based products after having full synthetic. I have also called several dealerships asking this question and they said the Kubota UDT and Super UDT do not reference ISO numbers. If there is another synthetic that you are using, I'd like to hear your comments too as Amsoil is not cheap. When searching archives, I saw someone who said they are using Delvic Synthetic but did not mention the source or cost. The Amsoil cost vary depending on the ISO. I await the wisdom of the forum. Thanks:anyone:
Here is the Amsoil linkhttp://www.amsoil.com/a/Synthetic-Hydraulic-Oil

Gator6x4 · Dec 7, 2011

The question about what oil to use, synthetic or conventional has caused a lot of flame wars on Tractorbynet.

I will share what I use without any additional comments: I use Shell Rotella T-6 in the engine of all Diesel equipment I own. I use the Manufactures Hydraulic Oil. Kubota Equipment Super UDT. John Deere the recommended JD Hydraulic Fluid.

I use Valvoline Synthetic gear oil where gear oil is required.

So far no engine, driveline or gear box failures.

Rice Rider · Dec 7, 2011

I am already using a full synthetic. If I can find one less expensive one other than Amsoil hydraulic, I'll be happy as a clam. No flames needed.

creekbend · Dec 7, 2011

Just a thought? Why not contact your local Kubota dealer and ask him for recommendations? Then, you can start the process of finding the cheapest sources for the recommended type or types. Good Luck.:tractor:

Rice Rider · Dec 7, 2011

I contacted two large dealerships that I thought because of their large number of tractors going through for service, that they would have an educated opinion and they both said they use the Kubota UDT and super UDT so no help there. Does anyone know what the ISO grade is for the L3400HST?

grsthegreat · Dec 7, 2011

My HST oil always looks like new when i check it...so whats the benifit of using a synthetic oil???

Rice Rider · Dec 8, 2011

I don't know why any Hydraulic fluid would get dirty because the system is a closed loop. I do know that the 500 hour service says to change it, so I plan on having the shop do that. I did not originally put the synthetic oil in it and I have been told on a number of occasions that once one goes to a full synthetic, you should not go back. So,......
1. Does anyone use a full synthetic oil in their Kubota? If so, what kind?
2. Does anyone know what ISO grade synthetic hydraulic oil to use on a Kubota? I thought this was going to be a simple post with several easy answers....Does anyone have an answer for the two questions above?

TripleR · Dec 8, 2011

Rice Rider said:
I don't know why any Hydraulic fluid would get dirty because the system is a closed loop. I do know that the 500 hour service says to change it, so I plan on having the shop do that. I did not originally put the synthetic oil in it and I have been told on a number of occasions that once one goes to a full synthetic, you should not go back. So,......
1. Does anyone use a full synthetic oil in their Kubota? If so, what kind?
2. Does anyone know what ISO grade synthetic hydraulic oil to use on a Kubota? I thought this was going to be a simple post with several easy answers....Does anyone have an answer for the two questions above?

It would be if very many people use full synthetic, but most of us don't.

I know it is accepted "wisdom" not to go from synthetic back to dino, but my brothers have done it in our cars and motorcycles without any problems and we keep our stuff a long time.

Sorry we couldn't be of more assistance.

gwdixon · Dec 8, 2011

Rice Rider said:
I don't know why any Hydraulic fluid would get dirty because the system is a closed loop. I do know that the 500 hour service says to change it, so I plan on having the shop do that. I did not originally put the synthetic oil in it and I have been told on a number of occasions that once one goes to a full synthetic, you should not go back. So,......
1. Does anyone use a full synthetic oil in their Kubota? If so, what kind?
2. Does anyone know what ISO grade synthetic hydraulic oil to use on a Kubota? I thought this was going to be a simple post with several easy answers....Does anyone have an answer for the two questions above?

1. Not this person.
2. Not this person.
Questions answered.

The information you have may be referring to using synthetic oil in the engine rather than in the hydraulic system.

Just put in quality hydraulic fluid and you'll be fine - especially with only 500 hours on it. The seals are not going to leak.

Max Power · Dec 8, 2011

Rice Rider said:
I don't know why any Hydraulic fluid would get dirty because the system is a closed loop. I do know that the 500 hour service says to change it, so I plan on having the shop do that. I did not originally put the synthetic oil in it and I have been told on a number of occasions that once one goes to a full synthetic, you should not go back. So,......
1. Does anyone use a full synthetic oil in their Kubota? If so, what kind?
2. Does anyone know what ISO grade synthetic hydraulic oil to use on a Kubota? I thought this was going to be a simple post with several easy answers....Does anyone have an answer for the two questions above?

the manufacturer doesn't test every oil on the market therefore do not expect any recommendations other then what they state in their manuals. If the oils meet the requirements then they are ok with the use of it. You would get a more direct answer from the aftermarket producer of the lubricant. (expect it to say "meets or exceeds OEM specifications" and mixing different products is not recommended")

As to whether the oil gets dirty ..YES it can (yes it does is probably more accurate). It is not as closed as you may think. It is vented to the atmosphere (means it breaths so moisture can get in).

there is wear in the system which also contaminates the oil and is hopefully trapped in the filter.

Oil also is under a lot of stress ...load and shear forces which do break down oils.

happy tractoring