>I have seen a lot of engines with the valves burnt after the first unleaded gas came out. Most modern >fuels have a built in additive to prevent this now. Marvel Mystery oil helps in some older engines too. >Just don't use it (or 2 stroke oil) in engines with an O2 sensor (It can be an expensive mistake!) To my knowledge none of the fuels today have any additive to protect valve seats. Might you be thinking of MTBE?? No longer used, it was an octane booster, not a valve seat protector. Marvel Mystery Oil is nothing more than a synthetic blend with some penetrates (like most of the other low cost valve seat additives). I doubt it would do anything to protect valve seats. In an engine with O2 sensors there's not much you can do other than install hard seats & valves if it doesn't have them. But hey,,, that's just ME!!! Bruce Hevner -------------- next part -------------- An HTML attachment was scrubbed... URL: http://splatter.wps.com/pipermail/amc-list/attachments/20080706/837b949a/attachment.htm _______________________________________________ Amc-list mailing list Amc-list@xxxxxxxxxxxx http://splatter.wps.com/cgi-bin/mailman/listinfo/amc-list