Posting late to this thread but might be of value.
Friend of mine, former smoker, asserted that he'd never had a BIC last more than months. Said they leak out.
I had a stash of BICS still in the package for years all still
full.
So I used one briefly. Then marked the fluid level and left it sit.
Just noticed it the other day. Was 3/4 full on 8/4/06.
Totally empty 12/18/06 (or earlier).

Unless you've checked your lighters recently for fuel level, don't count on them being anything more than a sparker.

Unimogbert