About 6 months ago I ordered a tire pressure from Longacre Racing through Roush/Yates racing, about 55.00. It has a pressure equalizer valve on the top of the readout scale that is used to equalize the the gauge to the current atmospheric pressure. The gauge also uses oil to help dampen the movement to sudden pressure changes.
I use the gauge often and have always opened the valve and closed it before use and I hang it on a rack in the upside down position to straighten the curly hose.
Anyway, I left the valve open and the dampening oil leaked out. I called Longacre racing and inquired about the oil it was filled with. After I found out what kind of oil it needed, I searched the internet and no joy on the oil so I called Longacre again and they shipped me a bottle of oil to refill the gauge, free of charge. This is what customer service is really all about.