Case hydraulic drive lawn mower

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Jul 10, 2004
I've got a couple of Case lawnmowers that are hydraulic drive and speced to use 20w40 oil. Since that grade of oil is not an easy one to find I use Rotella 15w40. It is also speced to use 5w20 in winter with temps below 32 degrees. Since I use a snow blower on one of them in temps well below 32, would there be any issue using Rotella 5w40 year round? I'd like to change my oil change interval to once a year from twice a year.
I tried Rotella 5w40 in my snowblower engine last winter and it was near impossible to pull the rope starter, going to 5w30 synthetic this year.. Since hydraulic oil takes a while to heat up to flow better, you might consider something lighter. If you went with a 5w30 synthetic, it should meet the summer requirement and still be winter friendly. I'm using the NAPA packaged stuff from Valvoline and would consider the stuff from walmart as well. Most hydrostat systems use 10w30 engine oil, even in forklifts.
This is not a hydrostat, it is a true hydraulic system, the engine turns a hydraulic pump which pumps oil to a hydraulic motor on the rear end.
Assuming this is a Case Hy-Driv, these do not use generic 20wt hydraulic fluids. 15w40 is perfectly fine in the hydraulic system on these garden tractors. This is what most owners today would use in the Hy-Driv. I used to own a Case 220 Hy-Driv, w/ 38" deck. I ran 15w40 in the hydraulic system as well as the 10hp Kohler K-series. I used 75w90 gear oil in the rear diff.
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My Ingersoll 4020PS uses 20w40 engine oil for the hydraulic system. A lot of users also use Rotella 15w40. I think the Case and Ingersoll are pretty much the same.
Yep, the name changed to Ingersoll sometime in the 1980s I believe. Same machine. I think the issue with 20w40 is it's hard to find, thus most owners using 15w40, obviously with the Rotella being a staple. My Case 220 was a 1979 model year. Back in the day, Case/Ingersoll recommended 20w40 for the Kohler K-series engines as well. Just for nostalgia purposes, here's a clip from my 220's owner's manual:
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