I just read your links and it appears one MAY be able to get the injectors rebuilt with newer materials that wouldn't degrade? Of course this costs and requires some work, but it seems feasible.

I could start with B20 and get the injectors rebuilt when there's some winter downtime.

Lots of good info there...looking to learn more. Do you have a source for parts and replacements like fuel and oil filters for older MBs?