Hi All , I have a Cub Cadet 3000 Series ( Heavy Duty ) that I would like to change the oil in the Hydrostatic . Can I use 5w30 or 10w30 Synthetic Mobil 1 for this unit.
If not what should I use ?
Viscosity is usually dependent on outdoor temp just like an engine.
Having used a 5w-30 I think it's too thin...a 10W-30/10W-40 and even a 15W-50 could be used. Like M-1 15W-50. Be sure it is at least 1200 ppm ZDDP...or higher.
I used M-1 10W-40 Synthetic Racing 4T over the weekend. It is a 4-cycle motorcycle oil with 1600 ppm of ZDDP which is really important for long life of the gears and pump.
It runs great and is very quiet for a 20 year old hydrostatic unit. It is made by Hydrogear.
It does cost near $10/qt and my unit takes about 3 1/2 qts.
FYI....I bought a pump from Amsoil (had an empty bottle from their oil.) After I drain I pump the new oil in from the bottom drain plug to avoid getting air into the system which could cause a "vapor lock" like situation and make it hard to work the air out.
I've got 3yrs/100+hrs on the Shell Rotella-T 15w40 in my Cub Cadet 2544's trans. Don't hesitate to use 5w40 or 15w40 in place of the $12/qt Cub oil. Your 3K series has an extra charge pump than 2K series, other that that, it's the same Hydro Gear BDU series hydrostat bolted to a Cub differential assy. These units hold 6qts and are a snap to drain/fill and change the filters on. So much so, I see absolutely no need for anything more than $5/qt.
Just out of spite to Cub cadet fluid prices i just dumped napa 10w40 i last fall with a wix filter and all is great. I talked to many on this forum including a few that had already posted on yours and confirmed that this will be okay. This summer i am switching it over to a 5w40 as it is very close to the cub fluid viscosity and has a stronger additive package than the generic 10w40. I run my tractor thru the winter so i chose the 5w40 instead of 15w40. Joel that posted above has done tons of research on this issue and seems to know alot about the system, maybe he could confirm if you need to spend the extra money on the 5w40 vs the the 15w40. Good luck and thanks for not supporting that stupid 13 dollar per quart oil scam.