I'm picking up euphonium (brass instrument) after a 5 year hiatus. Can I still use my old valve oil and slide grease (Trombotine)?
As the others have pointed out, no, it doesn't expire, but I never use old grease myself. You get lots of spit transfer from whatever you're lubing up to the grease/oil and the bacteria from said spit has just been.. sitting there. Growing. And possibly multiplying. Sorry. I'm a germaphobe. That's just yucky to me.
Valve oil would not expire, it would evaporate. If there is some left in the bottle your good to go. Slide grease, as long as it's not hard or discolored your fine. It could be dried out or possibly have some interesting growth in it if the container was not air tight. Most likely its fine.
Valve Oil--as far as I know, does not expire. I've had some valve oil for decades (I'm primarily a woodwind/string player, my occasion to use valve oil is rare) and it's still good. Slide grease--which hadn't been invented yet when I was in brass class--I am not so certain about. I'd recommend looking at it and rubbing a bit between fingers. It's probably OK but if there's been some degrading or separation of the ingredients--if it's turned gray or tan--then I'd buy new. Hm, I have some cork grease that's three decades old, and it's still fine--so there's a point of comparison.
Valve oil should be fine. Trombontine is for trombone slides (has a looser consistency than tuning slide grease) and I'd recommend going to the music store and getting some slide grease for your tuning slides, specific for valved instruments. :)
