HyTran in a Hydro vs. Gear Oil in a Manual Trans.

sawdustdad · #1 01-03-2013, 10:08 AM

I am working on my first hydrostatic cub cadet (my 149 project). About to drain and replace the hydraulic fluid and change the filter. (you wouldn't believe all the dirt that was caked around the transaxle and hydro unit on this tractor--packed under the fender unit. What a mess.) Anyway, the instructions say to break the rear cover and let the oil drain. Then, clean up, new gasket, reinstall the cover, and refill. 7 qts or so. I got all that. But it got me wondering if there is any difference in how the rear differential acts with hydraulic fluid in it vs. the gear oil in my manual transmission 108. Seems like the viscosity is a lot different, and the gear oil would be better, but the hydro units use hydraulic oil. Any thoughts or observations on this?

martyrant · #2 01-03-2013, 10:24 AM

Quote:

Originally Posted by sawdustdad

I am working on my first hydrostatic cub cadet (my 149 project). About to drain and replace the hydraulic fluid and change the filter. (you wouldn't believe all the dirt that was caked around the transaxle and hydro unit on this tractor--packed under the fender unit. What a mess.) Anyway, the instructions say to break the rear cover and let the oil drain. Then, clean up, new gasket, reinstall the cover, and refill. 7 qts or so. I got all that. But it got me wondering if there is any difference in how the rear differential acts with hydraulic fluid in it vs. the gear oil in my manual transmission 108. Seems like the viscosity is a lot different, and the gear oil would be better, but the hydro units use hydraulic oil. Any thoughts or observations on this?

Pretty sure because it runs your hydraulics and the transmission, not just the transmission like the 108. There are a lot of threads of Hytran vs generic hydraulic oil, but the main reason I see everyone go with hytran is it's superior ability to trap moisture. I think the consensus is that it's your cub and you can put hytran or generic in there, but I don't think gear oil would be something you want to stick in there since it runs your hydraulics as well (I'm a noob when it comes to this stuff, I'm sure plenty of the others will have better reasons as to not use gear oil in there).

I just changed the hydraulic oil in my 1250 and had to replace the rear axle seals after filling it back up, so try to pay attention to how much oil actually comes out of there (mine was a lot less than 7 quarts that came out, should have been a flag that there was a leak somewhere--and someone else had suggested to do the rear axle seals at the same time while it was drained, but I had no idea how to check if the seals were gone or not so I ended up filling it up to find out it leaked to just break it down again).

cubs-n-bxrs · #3 01-03-2013, 10:47 AM

A gear drive cub such as a 108 is suppose to have hy-tran or an equivalant hyd oil in it also.

sawdustdad · #4 01-03-2013, 10:32 PM

Quote:

Originally Posted by cubs-n-bxrs

A gear drive cub such as a 108 is suppose to have hy-tran or an equivalant hyd oil in it also.

You are correct! I checked the manual and that's what it specifies. I've never had to add oil to my 108, so I just assumed it was 80/90 weight gear oil like an automotive differential. Learned something new. Again. Should have RTFM.