RTV is a type of silicone. It is used for lots of different things, mainly on automobiles to seal up thermostat housings, manual transmissions, stuff like that. You can find it at any local parts store or wal mart. I always like the black RTV. When you use it don't glob and cake it on, a thin layer will do just fine. I had to rebuild the 6 speed transmission on my drag car because the previous owner used too much RTV and it mashed out inside of the transmission and ended up getting in the bearings and also behind the shims. Here is a link to what RTV is

http://www.permatex.com/products/aut...sket_maker.htm