I just stumbled across this technical paper that is devoted to
explaining about anything you could ever want to know about gasoline. I
haven't figured out the header info but it seems to indicate an
affiliation with MIT. If you want hard technical info on things like
where EXACTLY gsoline comes from, the precise nature of the incremental
changes in gasoline from the 1890s to the present, what causes valve
seat recession, and much, much, more go here:
http://www.moparpages.com/faq/Gasoline_FAQ_Part1.txt
The valve seat recession info is on page 4:
http://www.moparpages.com/faq/Gasoline_FAQ_Part4.txt
There is a LOT of info here. It would take hours, maybe days, to read
through it all.
Have at it!
Pete in PA