This isn't the most glamorous of subjects but it's long been a debate amongst brass players as to what, how much, when and which oil to use on valve instruments.
I dont claim to be an expert on the subject, I dont have an engineering or chemistry background but I do have 40 years experience as a cornet player and I think that I have pretty much worked this subject out now.
Ranging in price up to just over a fiver, it's all in the application. Little and often may be something that we are told about how we should treat ourselves but it's the same for your valves.
As valve oil is also a cleaner, then use it in just this way. Put it on... just a stripe on each side of a valve... wiggle your valves up and down (it's a technical term!), take your valves out again and wipe them down. Dont be alarmed by the dirt. No one is watching! This may need repeating depending on when you last cleaned your valves. Then simply put a stripe of valve oil down each side of the valve again and replace.
You should find that after the clean, your valves will be much smoother and slicker. Do this regularly. Thats the key and please... don't ever spit on your valves. It's not only unnatural but your spit contains all sorts of enzymes and bacteria that don't work well and will hinder your attempts at Flight of The Bumble Bee.
Good luck and my personal recommendation is Blue Juice.
