S65 Piston Ring Removal

I'm messing around with getting piston rings free. Here are some things I've tried:

Heat (enough to melt the thin sides of the piston
Two-Cycle oil soak
LaquerThinner & Tranny Fluid soak
Muriatic acid soak
Gentle prying (generally the best way to snap them.

What I've noticed from pulling the broken ring chunks out of the ones I get impatient with is that the rusty sticky bits aren't on the back of the rings but rather the sides. So I've been trying to get razor blades and lubricants in those side gaps to free them.

While I was thinking about this I thought, 'what's thinner than a razor blade?' and of course the answer is 'a feeler gauge'. So tonight I'll find a cheap feeler gauge and get started ruining it by sliding it around the ring to try and free it. The next logical question becomes 'what's the size to use?'

Enter the book:

Piston side clearance is 0.015 to 0.045 for compression rings and 0.01 to 0.045 for oil ring. Sizes are in mm.

Now, I'll have to find the same info later for S90 or whatever I'm playing with next week, but I don't NEED this info. It's just nice to know so I can use the largest feeler gauge first.

I don't really intend to reuse pistons OR rings unless I have to, but down the road I may be messing with an old Alstate motor where spares are not just hard but impossible to come by. Plus it's just nice to fuck around sometimes and see if it can be done.