[wnta1ss]

Found that the metal cap works alright if you note the orientation, it seems to seal better in a certain orientation, weird but that's what member Stephen12ZL1 had said and that seemed to work out. Mark the cap with a sharpie when you find it's sweet spot.

I used it only for pressure, did not put any fluid in it. Therefore no mess. With the cap orientation sorted out, not a problem to depressurize, top off the fluid, reinstall, pump back up, and move some more fluid.