I vote with Hamiam. Don''t try to treat teak. Our all woofden boat was built by traditional professional boatbuilders who follow the adage "what would our ancestors have done differently had they had the benefit of todays technology and matereials?" Hence they do like their epoxy
(when properly used i.e. from new entirely encassing timber.
On our deck they laid a complete marine ply deck fully encassed and laid teak over, again sticking it all down with epoxy
, and caulked (grouted!) with graphite dispersed in epoxy
. Hence incredible strength and durability. Just a regular warm water wash and a good bit of elbow with a medium scrubbing brush (not too harsh).