You don’t have to use preservatives or treatments of any kind to ensure the health of your teak furniture. Oiling or waxing teak is only recommended if you are planning on using the furniture indoors. Oiled teak which is used outdoors  is more likely to mildew and will be subject to irregular coloring as it weathers. New teak furniture often appears smooth and “polished” – this comes from the oil which occurs naturally in the wood. The oil on the surface of your teak will evaporate over time once the furniture is outdoors (hence the “graying”); it is the oil that remains below the surface that gives the wood its strength and durability. This is the best way to make your teak last all year long.