Don't Know for Sure, But I Can Opine
Dear Surfer:I'm not a wood expert, but a can convey what I have experienced, during many years of wood projects. Several years ago I put in new red oak floors in my home. The not used odds-and-ends were put outside to the pile that I clear out every few years when the quantity gets to be a dumpster load. After only year or so, the Oak was already beginning to split, was very discolored, and warped. Back inside, my wife didn't notice that a plastic catch plate had split under plant that was resting on the oak floor. So water was wetting the oak floor. This went on for about a week before I noticed severe discoloration of the floor in the area. The edges also had warped up.Oak will develop unsightly gray/black spots readily when in gets wet. This can be observed if sanded oak is wiped with water to raise the grain before sanding again and finishing.Even though you have varnished, H2O will ingress into the wood and with time and sun damage the finish will loose its ability to protect anyway.If you are looking for a teak alternative that is quite a bit cheaper than teak, you might want to consider IPE (iron wood). It is now a common (abeit premium) decking wood available at many lumber stores (in California anyway). Its rock hard and is rich in protecting oil, like teak. You can pick through the selection at the lumber store to find pieces that have the most appealing color and grain patterns. This month's Consumer Reports magazine did a report on decking materials. They rated IPE to be as durable as the newer synthetic deck materials. As with teak, it will weather to a natural gray color if left unfinished.regards,rardi