I have encountered thus far 4 different types of caulking. mineral spirits mixed with paint thinner has been working with steel wool, except for the silicone. for that, I'm using a wire brush on a power drill! its messing up the paint nicely, but id rather have it warm and dry and ugly then semi pretty and leaky. thanks so much! the roof still has to come down, but looking at it they only used leveling sealant on it thanks goodness, so mineral spirits should be all I need. the roof is one giant sheet of aluminum, with cut outs for the vents and such.