Fuel tank cap won't open.

[gs500e]

Hey, been a while since i was on here.  [I did search, but perhaps i missed similar issue]

Got my bike running for the year (haha seems every year i pay the price for not properly winterizing fuel system).

But.... i was going to look in my tank to see how much fuel was in there (like i could really tell by looking) but i could not get the cap open.

I took the cap apart and lubed and cleaned it all last summer (and it operated well since then).  So i know some of the 'goings'ons" with the fuel cap.

The key does not turn far enough imo.  I only have one key to the bike currently (lost two over winter some how) so i did not want to force it and break the key; but i turned it fairly darn hard.

I imagine the lock cylinder has become rusted/corroded over the winter, hence my issue.  Don't believe the cap can be removed without opening it...?.........
Any tips on freeing the mechanism so i can put gas in the tank?

[Paulcet]

Some sort of spray lubricant maybe. Also, my gas cap resists if I don't press down on the cap when I turn it. Relieving the stress on the latch makes it easier to turn the key.

[MVent03]

My friends bike did this. He used PB Blaster and let it soak for a couple hours. Worked first try.

[adidasguy]

#5003

Press the cap in hard when you turn the key. Those springs in the cap have a lot of force. Enough force that they can make you break off the key.