Stopping petrol leak

Hi all, I have a petrol leak coming from the petcock.
It is coming from where the petcock fits to the tank. Is it ok to fit a new fibre washer, or do I need a rubber type washer. Your thoughs please.
Nubsey

 

Cheap enough to replace whole tap.

 

Rubber and ethanol (in 95 octane) don't go so well, you should use a special type for petrol stuff. But as Marsh says, just get a new tap

 

Thanks for that, will get a new one.

 

New tap purchased and fitted. Problem solved.