1944 Farmall H - how do you drain hydraulics

Thank you.

The 1940's manual and purists say to use 30W _non-detergent_ oil in the hydraulic system. If you use 30W oil, make sure it is non-detergent (harder to find) as the detergent stuff will foam and the hydraulics won't work. After reading some posts here, I switched to using hy/trans oil (Wal-Mart is the least expensive source). If the system doesn't have any leaks, this oil works well and gives better wear protection in all temperature ranges. Also, if you switch implements between this and other tractors that use hy/trans oil, you don't have to worry about mixing unlike oils.

If the system doesn't have any leaks, I'd work it a bit and then drain and fill it again sometime soon to flush the age and wear sludge out - waiting until a rebuild to get it completely clean. If it does have leaks, it's only about $30 from Carter and Gruenwald for all the gaskets and balls and springs to rebuild it.

These are mostly my opinions on the matter but this should get you going.