I don't understand why using the washer on the plug would cause galling while removing them doesn't. Most of you guys seem to be in agreement on it so there must be some truth to it.
I would expect a plug with no washer would compress the tube end, drag against the aluminum while tightening, and work harden it until it chips off. I would also the expect a crush washer to somewhat prevent that.
But the opposite is true??? I've been using the crush washers on my own Hemi since I built it in 2016, so far so good on the tubes, but I'm open to change if there's a good reason.
You reduce the effective surface area by using the washer which increases the “unit loading” which galls the tube.
The tube acts as a seal, pinched by the plug and head, it conforms to the plug and head. I have actually had to use a few tubes that were jacked up. By repeated tightening and loosening you can sometimes salvage the tube in a pinch.
(A similar galling issue - using the incorrect head gasket on an aluminum head).
