I've read one should use a shop vac to slow or stop hydraulic fluid leakage when replacing filters. I've not seen any information how to accomplish this. I discovered the hydraulic cap on my tractor was a common on inch male NPT fitting. I grabbed a one inch socket to male NPT adapter, cut a short piece of one inch PVC to jam into it then grabbed a one inch PVC coupler to slip over the other end of the PVC. Putting a couple wraps of biseal tape around the outside of the coupler made it big enough to pressure fit into my shop vac hose. I put it all together, turned on the shop vac to apply a vacuum, and proceeded to replace my filter with only slight leakage.