Here is an article written by Gordon Millar, from our Master Index file, in the Fuel and Additives section. Gordon agrees, that additives are not necessary, although I have been known to dump a little valvtect or MMO in my fuel. Is it worth it? Probably not. Using the top grade motor oil with zinc additives is probably a lot more important.
http://www.network54.com/Forum/424840/message/1137252880
Paul