How to Oil Trumpet Valves
The first time you use Ultra-Pure Professional valve oil, or when you are changing brands of oils, you should clean the trumpet or rinse off the old oils with the new oil. See our tips on How to Clean the Trumpet if you want to give the trumpet a full cleaning. Otherwise, just remove the valves and the bottom valve caps, being careful to see how the valves will go back in their casings (in most instruments, the valve number faces the mouthpiece end, but not always). If the valve caps are stuck, try using a rubber jar opener to get a better grip. Using pliers will damage the valves, so if you can't remove the caps, take your horn to a music repair shop.
After removing the valves and bottom caps, put the horn over some newspaper and squirt plenty of oil down the casings and the valves to remove the old oils and grime. Carefully put the valves back into their casings. Rotate them just enough to "click" the valve guides into their slots. After the valves are back in their casings, blow some air down the leadpipe while moving the valves. If air stops moving, you probably have one or more valves in backward.
Wipe off the bottom valve caps before putting them back on the horn. After two heavy oilings like this, you will have removed all the old oils.
Pro tip: If you are in a great hurry, you can pull the valve part way out of the casing and drip a few drops onto the valve surface.