When I have left a small amount of fuel (Duraglo 16) in my nitro race car overnight, what's left is darker and does not run the engine too well. The LHS owner said that this because the nitro evaporates and leaves a potentially damaging residue.

Now, for my flight box I have a modified fuel container cap with two holes in it, one with a metal fitting to join the pump line and the 'clunk' line. The other hole is used as a 'breather' hole. I've yet to use it on the bottle of fuel (Duraglo 5). Is it ok to leave it all in situ and not worry about the fuel going of during the next few days / weeks ? Or do I have to plug the breather hole and / or the fuelling 'nipple' ?

Fuel info is here

[link]http://www.aabt-collectibles.co.uk/cat443-434.htm[/link]

Thanks