This video I'll link to explains leaks perfectly. The flanges crack and need replacement. It's an easy fix. If you own a scepter can you need to understand everything in this video. I have 11 cans to go to the sand dunes. I carry 8 and have fixed at least 5 this way. I keep a bag with a couple of complete caps, flanges and the proper viton gaskets made for gasoline because they need maintnence from time to time. Check your gasget per the vid and check the flange really well because sometimes the crack is hard to find and only leaks a little bit. Buy spares if you need to order because eventually the flange will crack. Silicon spray on the flange, gasget and cap threads helps them from sticking when the can swells up in the heat. Also be carfull when you fill them because the soft plastic sealing surface on the cans can get dinged up from the gas snozzle. Protect this area of the can. If you have bad gouges clean them up the best you can. This entire 5 minute vid needs to be understood along with what I added.If the seal is seated they are fine. The only problem ever with the scepter MFCs is getting the caps the seat just right and seal tightly. Out of (8) I own no matter what I do one always weeps. Anymore I lean toward rotopax for the flexibility of mounting but since I have these cans I just can't justify the cost of more.