TeakGuard vs Cetol etc.
 

Never heard of teakguard lasting only 3 to 4 months. Did you clean it
according to the instructions? I have been using teakguard for a while
and have always had it last 1 year at the very least. BUT you must
clean it with a good quality cleaner. If you do not clean it according
to the directions you will not get good results. And bleach doesn't
work, it has to be a teak cleaner. The teakguard company makes a very
strong, safe cleaner and is cheaper in one gallon kits anyhow. If you
need a lot westminster teak gives bulk discounts.