Quoting Removed, click Modern View to seeThere is on ingredient that is in a few brands that cleans varnish out of a fuel system more effectively. I spent part of the morning trying to find what it is called. I ran into it about a year ago, but have had no luck this time. It doesn't show up on a MSDS sheet for seafoam due to manufactures trade secret.
https://seafoamsales.com/uploads/2019/09/SDS-SFMT-US-ENG-v20190905-1.pdf