Ask and you shall recieve! (Flip Top Gas cap Adapter)

What kind/type/brand of sealer are you guys using on these? Mine continues to leak behind the adapter & run down the side of the car. :sad2: I tried #2 Sealer, it says it is resistant to gasoline but when I took the cap off earlier it was almost all dissolved. If it is going to leak I will have to go back to my old OE cap & sell the adapter. I love the way the flip top cap looks & do not want to switch back. :crybaby:I need some advice! Went to the local parts store & none of the guys could recommend anything. I remember back in the day there was always at least one guy at every parts store that had been there & done that; not anymore. Thanks in advance.