I am planning on going to the lake with my grandpa soon and I was just wondering is the gas inside of my grandpa's boat still good? It's been sitting in my grandpa's basement over a year. It's an old 1970's Riviera Marquis (i hope i spelled that right) boat with a Mercury engine. We had work done to it in 2009 and had the old gas taken out of it. We put gas into the boat later in July 2009 and we hadn't been to the lake since. There's still a good amount of the gas in the tank, but I just curious if the gas is still good or do we need to take the old gas out due that the boat is old? The boat still looks new btw.