What oil for summer and winter in Sundstrand U15 hydrostatic tranny?

[reader2580]

I have a 1995 commercial mower with a Sundstrand U15 hydrostatic transmission in it. I use the mower year round with mowing deck in summer and snow blower in winter.

The manual calls for 10W-30 or 10W40 oil in the summer and it calls for type F ATF in the winter. Could I use a synthetic motor oil or something similar that I can use year round. I don't want to change tranny oil twice a year, but 10W30 oil makes the hydraulics very sluggish on a winter day. The power steering and hydraulic lift for the snow blower barely work on a cold day.

 

[big bubba]

something like rotella 5/40 T6 syn could meet your needs year round and should be compatible given it calls for a std 10/30. maybe let it warm up fully for at least 10 or more minutes in the cold...you might post this also in general lawn & garden forum. can you contact your manufacturer on year round oil as well? some may suggest a 0/30? syn, but i hesitate to suggest. you'll probably get a lot of response on this.....best regards

 

[reader2580]

I tried calling Toro and they just say to contact your local distributor. I went to the local distributor and they didn't know because they aren't supporting too many 20 year models these days. These days Toro limits what dealers can sell and support their high end commercial products. This unit is much more like a compact tractor than a typical riding mower. It has a full hydraulic system and it has a liquid cooled Mitsubishi diesel motor. A replacement unit from Toro would cost in excess of $20,000.

I think I'll just have to give up and just change the hydraulic oil twice a year. Would letting the unit idle for 10 minutes really warm up the hydraulic oil in the winter?

 

[oldnslo]

I agree with Big bubba and use a synthetic fluid will give better performance in both cold and hot conditions

 

[big bubba]

with that kind of replacement price, i would verify somehow that something like rotella T6 would be comparable before using. it should, but i won't say for certain. in terms of warm up, after 10-15 min, maybe cycle through the hydraulics action a few times before putting it under load. best regards

 

[George2615]

Your post is confusing a little. You say your mower has a hydrostatic trans in one sentence then talk about motor oil in the next.
For motor oil you can use 0W-30 or 5W-30Rotella T6.
Are you sure the manual calls for 10W30 or ATF type F for the hydrostatic. If so you can run ATF type F year round.

 

[reader2580]

Your post is confusing a little. You say your mower has a hydrostatic trans in one sentence then talk about motor oil in the next.
For motor oil you can use 0W-30 or 5W-30Rotella T6.
Are you sure the manual calls for 10W30 or ATF type F for the hydrostatic. If so you can run ATF type F year round.

The manual specifically calls for motor oil for the hydrostatic transmission, 10W-30 or 10W-40 for 32 degrees to 90 degrees. For below 32F the manual recommends type F ATF. I am hoping with newer oils in the past 20 years there is something that might work for both summer and winter.

I found a current manual for the Sauer-Sundstrand U15 transmission and they don't even list motor oil as a choice for fluids. They list regular hydraulic fluid and type F ATF, but they also say to see your equipment manual.

 

[big bubba]

if that's the case Rotella T6 should do for warm weather use. cold use is a toss up. my suggestion is to try T6 for winter use after warm up & cycling through hyd/hst range before using. am sure you have a spin on hst filter? guess i'd recommend annual change on that too, esp if you're using 2 different viscosities/type of oil. tough call. somewhere there's a syn for your application full year. as suggested, post this also in lawns & garden forum for a wider audience. might check out Mobil 1 oils as well...... best on that bb

 

[10ecfarmer]

How bout one of the 0W-30 motor oils???
But, if it was my machine I would try T6 Rotella first..

 

[reader2580]

Yes, I have a spin on filter. I have a new filter to use once I select a new oil. What I am trying to avoid is having to change the transmission oil twice a year. The ideal would be to find an oil that is thin enough for winter, but also thick enough for summer. I assume I have 10W30 now and the oil is so thick in the winter that the hydraulic cylinders can barely lift the snow blower at start up in 15F weather.