Fuel cap rusting onto filler neck

[purplepeter]

A bit of a strange one.. My filler cap has started rusting itself onto the filler neck inbetween fill ups
Obviously I'm inclined to give it a finger full of grease, but the question is.. What kind of grease do you reckon? Lithium, silicon, copper, moly or red rubber grease?
Any opinions please?

[broady_6]

Id go with copper or graphite any seize type. I expect itll need regular replacement as the fuel will wash it away. Interesting issue that I shall ponder

[937carrera]

I wouldn't go for copper, never sure where all those particles will end up, especially on a FI engine.

I have seen this a couple of times, I think I just put some engine oil on the filler cap and neck and rubbed it in. Massage for your fuel filler

[purplepeter]

Ahaa... Engine oil.. Good call!
It appears to be just rusty at the very top edge of the filler neck where it seals against the rubber seal, though I might suspect the threads of the cap need a clean too.. will give it a go

[Rob 400e]

While we are on the subject my filler tends to leak slightly on a full tank, I assume it’s the rubber seal. Does anybody have a good one for sale?

[purplepeter]

Perforations in the steel filler neck are fairly common, which can be brazed up. Also check the J shaped vent pipe
I'd have thought a Beetle filler cap seal would fit

[Rob 400e]

Cheers will add it to the growing list of jobs to do!