Meh, I accidentally tasted It when I used too much and It tastes like licking a 9 volt. Soo... that made me a bit cautious, i know its probably safe but I figure its trying to prevent the locking ring from sticking so no sense gunking up the whole tube connected to the mouth piece, my opinion so take it with a grain of salt, if you want to lube the whole stem up go nuts! It just seems like with excess a lot of the lube will go down the inside of the air path. All I can think about is a scenario where someone doesnt like cleaning or cant at the moment, and then repeatedly uses the lube to fix the problem. Liberally use lube on it a bunch of times (Probably 4-5 times with out cleaning) could result in lube making its way down that tube into the oven.
I personally dont want to vape lube. It is really slick stuff too its not thick, its super watery, I can see this making its way down to the oven when its heated no problem if used enough. My 2 cents.