When I first got into the wood restoration field my company name was Teak Works. I cleaned, sanded and maintained teak on yachts, boats, etc. Well that quickly led to decks, fences, cedar roofs and log homes. With offices in two states and the experience of restoring and treating over 3000 wood decks in the last 10 years I can honestly say that the application of an teak oil is not the best choice for this deck. While teak oil will protect the wood it will not give it the U.V. protection it needs. Thes oils are fine on swim platforms of boats, but that is as far as I would go with it. In My original post I mentioned that that I doubt the deck is actually teak, but another wood from South America that is vey similar. If your client wants to maintain the natural beauty of the teak or other exotic wood I again would suggest a penetrating oil based preservaive that is thinned and has a pigment to give it the U.V. protection it needs. Some varnish like marine finishes might work well on the deck, but, will make maintenance impossible. I am just trying to steer you in the right direction from my experience. Again if you have any questions, please give me a call.262-251-1737. Tim Cross