The third valve on my Olds Ambassador, and my Martin Imperial have been sticking. I've cleaned the casings and valves throughly, checked for burs etc., and tried different oils, but obviously not the right ones. So I decided to perform a test. I cleaned casing and valve throughly, and put the valve in WITHOUT OIL! They work perfectly! But the danger I fear is that dry metal on metal will have a negative result in the long run. The oil I've been using is Ultra Pure, and it seems to be fine in my other horns. I need to find an oil that will work in these horns without causing the third valve to stick. I'M OPEN TO SUGGESTIONS AND GUIDANCE?