I used to have an old Porsche 914 that had an oil pressure light that came on at low psi. When I added a gauge, I also added an annoying/loud piezo beeper that sounded when the light went on (approx. 10psi). This came in very handy during autocrosses..

So for a VX, you'd need the 914 oil pressure sender (or equiv.) and a light and/or piezo beeper from Radio Shack.