ive been reading about it and 10% seems to be the borderline and anything higher than that would do some damage. i was curious because some statons are mixing the stuff but dont advertise as so. reason being is that advertising for it just pushes up costs. mostly, it seems, this is being done by some smaller players in the petroleum industry. i really dont like to mention any but im going to make sure i dont put it in my bike.The real downside is that the ethanol just loves to attack steel components within the fuel system. It does a nice number on zinc plated fuel lines also. This will cause rust which builds up in the fuel filter, and eventually clogs injectors. Most newer vehicles have all stainless steel fuel components to be more compatible with gasohol.