I found this list on the internet of gas saving tips...most of them are well-known stuff, but there are a few interesting ones, right at the bottom - most notably, 'use a graphite motor oil'.
http://www.howtoadvice.com/savinggas
You don't hear much about graphte motor oil anymore, and I don't think there are any marketed in N/A now. I've read the threads on Arco, and how their graphite oil flopped years ago.
This is a fairly new list, so I am suprised that they mention graphite motor oil, but not regular synthetic oil for saving gas...Synthetic is much easier to get than graphite oil or additives, but there is no mention of them....weird!
Also interesting that they mention using MMO in the gas to save it, as experimenters on this site have found that sometimes the exact opposite happens, but the motor is smoother......