Motor oil used in hydraulic system

[Dutch Star Don]

My 2 cents......Just fill it with what's already in there. Monaco used three different fluids and wrote conflicting Manuals. Just replace with the same.

[bdpreece]

Since I just purchased our 08 Endeavor I have not actually looked at the fluid but my manual says the reservoir is filled with 15W-40 motor oil from the factory. Later on the same page it tells me to check the oil level every 6000 miles or three months and further down says "If adding of fluid is required use only 15W-40 motor oil." I would think once might be a misprint but twice leads me to believe that 15W-40 is what I have.

[OnJa]

I being a retired car hauler [truck driver], also say that you can use ATF in your hydrolic system, as that is what we used in our rigs.