Keystone Fuzion/Raptor locking gas tank caps

You need to be careful what off brand you get. The vapors can escape through the cap and over time you will loose fuel and have the smell of leaking gas. Not all caps are designed for the neck and threads of the vehicle/ rv you may be using. I had this issue for my Duramax. I always smelled diesel, but no leaks. Changed the aftermarket locking fuel cap to the right one, problem solved no more smell.