10W40 USED FOR HYDRAULIC

[Don R]

Hello. I have a small dig-it machine with a loader and backhoe. 18 hp gas engine. The hydraulic system uses 10W40 SF-CC oil. Is there a synthetic i can use for this? What would be the best oil to use.
Thanks for any help.

 

[IndyIan]

I'm no expert with hydraulics, but that is an engine oil spec from the 1980's. I wonder why they spec'd that over hydraulic fluid? I assume it doesn't share oil with the engine? Does the hydraulic oil get extremely hot?
Does this have a good hydraulic system filter? If not, you might be further ahead to run cheaper oil for shorter intervals, than an expensive synthetic for longer as I doubt you are running this too much below freezing?
I doubt there's any reason not to run a heavier weight tractor fluid, or any name brand 15W40 diesel engine oil? But I'm no expert, my experience has been with my tractor which probably runs a similar size hydraulic pump, but the same fluid is also in the gears of the drivetrain, and HST. It has a big hydraulic filter and another for the HST, and the fluid stays very clear on the dipstick over the 400hrs interval, so if the hydraulic fluid is discoloring on the dip stick, on your machine, its probably time for new fluid.
I would try to find a dig-it forum, or talk to local hydraulics shop, they may know of a reason a machine like that need engine oil and not hydraulic fluid?

 

[Don R]

Thanks for your thoughts. Not sure they stopped making these in 1990 I believe. Has been running with regular 10W-40 and did fine i think. Stayed clean and looked golden still. Im replacing because 2 cylinders had to be resealed so figured I would change it all. Has screens in the output and input of pump i believe but doesn't have a regular filter. There is a company, Maverick, that sells some parts but others are no longer available. I might reach out to them to find out why. My thought was it's not heavy enough, but seemed to work well since I got it last year. The engine oil is separate. But hydraulic pump is run off the engine spline.The transmission is hydrostatic and has its own filter and reservoir. It does say 10W-40 SF-CC Rated oil in the manuel, just don't know if thats available or recommended in synthetic. Thanks again for your thoughts.

 

[fozzdesy2001]

Go for it! I 10w-30 speced as hydro fluid in my chipper from that era, and it works good, T-4 15w-40 is easy to find and is a great value

 

[IndyIan]

Thanks for your thoughts. Not sure they stopped making these in 1990 I believe. Has been running with regular 10W-40 and did fine i think. Stayed clean and looked golden still. Im replacing because 2 cylinders had to be resealed so figured I would change it all. Has screens in the output and input of pump i believe but doesn't have a regular filter. There is a company, Maverick, that sells some parts but others are no longer available. I might reach out to them to find out why. My thought was it's not heavy enough, but seemed to work well since I got it last year. The engine oil is separate. But hydraulic pump is run off the engine spline.The transmission is hydrostatic and has its own filter and reservoir. It does say 10W-40 SF-CC Rated oil in the manuel, just don't know if thats available or recommended in synthetic. Thanks again for your thoughts.

Interesting machine with its own HST. All engine oils are supposed to be "backwards compatible", so there's no problems running the new available oils in older engines. So current Rotella 5W40 or 15W40 will work fine, as there's not many(any?) diesel rated 10W40 motor oils available now. It's probably best to stick with engine oil as that's what's been working so far and hydraulic fluids have different base oils, that maybe the seals weren't made for? I wouldn't change over now anyways, as it sounds like its been running well with what you are doing.