The prevailing wisdom is to always remove the plugs cold.

But being a contrarian, I always do stuff the wrong way 'round.

Aluminum has twice the coefficient of thermal expansion as iron, so I'd get that sucker as hot as possible and break the plug loose -- and then let it cool for several hours before removing.

The hole gets bigger (it's not the same as a sponge absorbing water). Don't you remember the 9th grade science class demonstration with the steel ball and steel ring? At room temp the ball won't fit, but if the ring is heated in the Bunsen burner, the ball fits through.

I do not believe that Kroil or PBlaster (and I have both) will effectively pass the spark plug gasket. It's not magic, just a very low viscosity, low surface tension oil. (However, once breaking the plug loose you could squirt some oil in at the gasket.)

Use nickel-based anti seize grease on the plug threads when you reinstall and you won't be faced with this question again.
--
Don Foster (near Cape Cod, MA)