OH-HM 42 oil?

   / OH-HM 42 oil? #1  

geoweaser

New member
Joined
Dec 14, 2022
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13
Tractor
Zetor 3320
I need to add oil to my Zetor 3302's hydraulic steering. The operator's manual calls for OH-HM 42 oil.

Could someone help me learn what that is and how to find it (or a suitable replacement)?
 
   / OH-HM 42 oil? #2  
I went partially down the rabbit hole, and it seems that HM is an ISO performance specification (ISO 11158 HM). The 42 is an ISO viscosity rating. I could not find any reference to OH.
I think you would want to call a Zetor dealer, or perhaps a Zetor owner here will be able to offer more specific advice.
 
   / OH-HM 42 oil?
  • Thread Starter
#3  
Thanks for looking into it.

I just found this description on a different page in the manual, which I'd overlooked: OH-MH 42 "meets the requirements for high-pressure hydraulic oil identified abroad as HM 32". Does that open up any possiblities for readily available hydraulic oil?
 
   / OH-HM 42 oil? #4  
I am assuming the 32 and 46 are ISO viscosity grades. If that's the case it would seem that your manual is saying a slightly thinner hydraulic oil of 32 is also acceptable.
If your power steering is separate from the transmission / hydraulic sump, I would start checking various hydraulic oils available in your area that meet the ISO specification ISO11158 for HM hydraulic oil.

A similar model Zetor manual has the same OH-HM 32 listed, but also adds "This oil corresponds to high pressure hydraulic oils according to ISO 6743, ISO -L- HM 32".
 
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