Mixing Hydraulic Fluid & Oil

[brt]

I recently purchased a 1999 763F. I have no contact with the previous owner and don't know if he used hydraulic fluid or multi-grade oil in the hydraulic system (not the chain case). I took care of a few slightly leaking connections and want to top off the system. What fluid (oil or hydro fluid) should I use? Can they be mixed? I would rather not drain and refill the entire system when I only need to add less than a gallon to top it off.

 

[Tazza]

Mixing oil shouldn't be a problem, they are compatible.

 

[Cal Blacksmith]

Years ago when I bought my 763 used from the dealer, I asked about fluids and told the service guy that I was using Delo 400 for engine oil and he said that it was great oil and could be used as hydro oil also. I have owned my BC for about 6 years now and that is the only oil I use for the whole machine, no problems so far!