RK37 hydro transmission oil

[mcfarmall]

My BIL just bought an RK37 hydro and I was reading his owners manual when we got together for Thanksgiving. I was a bit surprised that the recommended fluid was SAE 80W for the transmission. I understand that RK also makes a gear drive shuttle shift version of this tractor and might possibly conclude that this may have been a typo as I don't recall seeing a column for hydro and shuttle.

So I'm reaching out to some other owners to get a consensus as to what your manuals call out for oil.

From my knowledge of hydros in general, I would expect to hear a universal common sump oil would be recommended. I'm a Kubota owner so I would use Super UDT if I had a Kubota hydro. I would conclude that RK would use a similar fluid specified by TYM.

 

[DonRybak]

I have a 2018 RK37HC and when I did my 50 hour service I just went to Rural King and had the lead tractor guy get me the items I needed. He gave me the jugs marked as transmission/hydraulic oil like shown in the manual. The issue that most folks have is that the oil is clear and hard to see in the sight glass. I was adding oil and then checking the level in the glass and would up over filling it. I think that since there will be some residual oil remaining in the system it was closer to being a little over 8 gallons rather than the 9.25 specified. Best way around this is to buy a couple bottles of the John Deere oil dye that changes it to a bright red. One bottle dyes 5 gallons of oil. Just remember that if the tractor is taken in for service that it's mentioned that it's dyed transmission oil and not red hydraulic fluid.

 

[mcfarmall]

Thanks for the reply. Those numbers you provided are much more aligned with what my experience tells me. I think my BIL's owners manual has some bad/missing information. Can you imagine the disaster if someone put a full load of 80w in a hydrostat??

 

[DonRybak]

I found the reference you were mentioning about using 80W oil. It's on page 5-8 in the manual. Not sure why that's in there unless maybe the shuttle shift uses that oil rather than the trans/hydraulic combo and someone screwed up when converting the manuals from Korean to English.