if you are handy you could probably build a tester using a cheapo oil pressure gauge kit for around $30, you may need to scrounge around to find a fitting to fit the top of the banjo bolt on top of the filter, i work in a salvage yard so i just found another banjo bolt and drilled/tapped it so i could keep my stock bolt with it's bleeder incase of a problem with the gauge on the road i could put it back in, so i never checked what kind of thread the bleed screw had