If you are in any place that gets to 40 degrees or lower drain all the hydrolic fluid you can out of the system and change the filter and go to a gas and oil bulk plant and get some Air craft hydrolic fluid . Your boom will work at -40 below like its 75 out side and will mix with what old oil is left.
This is CABL.com posting #125216. Tiny Link: cabl.co/mGJM