When I have been working on repairing one of my older Kubotas, I often would get hydraulic fluid spilled all over the place. I know that caps are handy, but I use disposable foam ear plugs. They fit into the 3/8 lines very well, seal well, and come out when needed leaving nothing behind to mess up what I am trying to fix. At less than 10 cents a piece they are cheaper than oil dry to clean up later.