I have had a Poulin Pro chainsaw for about a year and shortly after using it the gas cap started getting a little tight. It has progressed to the point now to where it is almost impossible to turn even with pliers. I emailed poulin about it. and this is what I found out: We have seen this. It is not the cap, it is the new gases with the ether and the ethanol causing the caps to swell. If the cap is set out in the open for a couple of days, the liquid will evaporate and the cap will go back on. I have had a few customers tell me they have bought an extra cap so they can swap them back and forth. So if anyone else is having this problem this may shed some light on it.