My gas cap isn't sealing completely. I had a locking one on there and took it off because I figured the seal went bad on it. Put the original back on and I can still smell fumes a bit. I tried cleaning the filler neck where the seal contacts and the seal of the cap but it didn't take care of it. This cap was only used for around 3k miles and is just a few years old with what looks like a silicone seal on it (orange) instead of the regular black seal that the locking one has.
My next thought is to try putting a thin layer of dielectric grease on the silicone seal. Is this a bad idea? The only downside I can think of is that it may catch more dirt and need to be cleaned more frequently. Worth a shot?