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CAT 966: mixing ISO 32 and SAE 10 oil in hydraulics

swampdog

Senior Member
Joined
Sep 25, 2008
Messages
393
Location
Canada
This thread started as part of a thread in the Wheel Loader section. I asked, among other things, what oils I should run in my Cat 966C transmission and hydraulic system.

What I deduce from the discussion is that, for our climate conditions in Canada, the transmission should have a TDTO TD/TO-4 oil, maybe a 30 weight in the summer and a 10 weight in the winter. And the hydraulic system should have a TDTO TD/TO-4 10W year round.

I just talked to the original owner of the machine and asked him what they ran in it. He thought they ran CAT oil in the transmission, but didn't remember what type. For the hydraulic system, he thought they used CAT Hydraul 32.

From the info I can find, the CAT Hydraul 32 must be an ISO32 oil, which is about the same viscosity as a 10W oil. But there are other differences between the ISO32 and 10W oils.

So one question I have is whether I can add TD/TO-4 10 W oil to the ISO 32 oil in the hydraulic tank without damaging anything. The system is a little low and needs to be topped up.

Another question is whether it is acceptable to top up the transmission oil, not being sure what is in there now, with a TD/TO-4 10W. It may have a 30W in there now, and who knows if it has a TD/TO-4 oil in there now.

Since the oils look very clean, I guess I don't want to change everything unless it is necessary. But more than that, I don't want to damage the hydraulic pump or the transmission.

Info from anyone knowledgable about these oils will be much appreciated.
 

WhyWhyZed

Well-Known Member
Joined
Feb 14, 2008
Messages
147
Location
Canada
And the hydraulic system should have a TDTO TD/TO-4 10W year round.
If you are using Cat oils, it's HYDO, in the hydraulics, but yes 10W year round. TDTO is acceptable to use in hydraulics, but it's not Cat's first choice and I think you'll pay more for TDTO than for HYDO.

For the hydraulic system, he thought they used CAT Hydraul 32.

never heard of "Cat Hydraul" - again, Cat calls their Hydraulic oils HYDO.

From the info I can find, the CAT Hydraul 32 must be an ISO32 oil, which is about the same viscosity as a 10W oil. But there are other differences between the ISO32 and 10W oils.

just different scales - If you have a Shell Lubricants handbook, somewhere in the back of the book is a chart x-referencing the different scales.

So one question I have is whether I can add TD/TO-4 10 W oil to the ISO 32 oil in the hydraulic tank without damaging anything.
no problem, and TDTO is fine in the hydraulics, but again - HYDO is Cat's specific hydraulic oil and the first recommendation

Another question is whether it is acceptable to top up the transmission oil, not being sure what is in there now, with a TD/TO-4 10W. It may have a 30W in there now, and who knows if it has a TD/TO-4 oil in there now.
for topping up you'll be fine to add TDTO
 

willie59

Administrator
Joined
Dec 21, 2008
Messages
13,396
Location
Knoxville TN
Occupation
Service Manager
Topping up with lighter oil is O.K. Topping up with heavier oil is not recommended.

I agree. I'm still scratching my head over using 68 oil in Nova Scotia. What's up with that? :beatsme
 

Johnsoils

Site Sponsor
Joined
Jul 28, 2008
Messages
72
Location
Iowa
I know synthetics are more expensive; but give them some review folks. You won't have to switch viscosities from summer to winter. They also keep you system running cooler and reduce wear. Running a cooler hydraulic system means longer hose and component life. Synthetics are also able to withstand higher temperatures without breaking down like conventional fluids. So please, don't let sticker shock steer you away from synthetic fluids. With routine oil analysis and extended oil drains intervals; they will save you money and reduce your downtime.

Thanks,

John
 

DPete

Senior Member
Joined
Feb 21, 2007
Messages
1,677
Location
Central Ca.
I contacted Chevrons lube tech center and asked what hydraulic oil the sell that is compareable to Cat HYDO 10w. their reply was Chevron Drive train SAE 10w. The last pail of Cat oil I bought was near $20 a gallon
 
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