Al,
What brand is your hydraulic lift? Pictures?
On mine, inside the thick round housing is a large piston with 4 cast iron rings. The manifold valve pushes the piston in the upward direction and the oil is diverted through an external bypass tube for the downward cycle. It is a one way cylinder, no power down function just gravity. Refreshingly simple design.
I think once you lift up the bed with your front end loader you will be able to see where you can add oil. I used 10 weight hydraulic fluid and it took approximately one gallon. Just keep in mind that if the cylinder is low on oil it means that one or more (most likely all) of the packing seals are worn out. Don't kill the pump by running it dry.
Paul
