Originally Posted by JHZR2

You are right, I missed that detail.

I’ve generally observed that those little rings shrink and harden pretty fast. My cars don’t see a ton of mileage so they see two year or more OCIs backed by UOA. Thus keeping good rings on there is helpful.

Interesting that the 617 fits a 7mm ring (so a 6mm must not seal), but I guess the design in the 602/603 is slightly different so it will only fit 6mm rings?