Fuel inside bottle smells, easily spilled; fuel also evaporates easily . I use a piece of Saran Wrap forming a barrier between the lid and the bottle when we screw the lid on. We also keep the entire  fuel  bottle in a large, sealed Baggie, in case this spills. We keep some rubber bands on the bottle for what-ever.  Otherwise, if it’s filled up  and liquid sealed, it’s fine.