Next time use TWO filter wrenches on the filter. The torque with one has you fighting against yourself... Only took me two days back in the winter to learn this from a REAL mechanic...

That is a good idea, heat gun. I bet that would work. If someone ever brings be a stuck one again, I will try that first, before the chisel

Air chisel works great. Your not cutting but the action of the air chisel will loosen it up. Been there done that. It works.