Date: Mon, 17 Feb 2003 19:09:53 -0600 From: "Walt Kienzle" <wkienzlenopsam.net> Subject: Re: Gas Grade Question
I think the "AON" you are reading is actually "RON", Research Octane Number. This is the method used in Europe to measure octane, and that is what the "R" in (R+M)/2 stands for (the "M" is for "MON", Motor Octane Number, which once was used in the US as the standard for measuring octane). Now, in the US, they just average the two numbers, hence the formula: (R+M)/2. Octane given using this average is called the "AKI", Anti Knock Index. 93 RON would be about 87 AKI (that would be regular here in the US) because there is about a 4 or 5 point difference between RON and AKI, depending on the grade of gas. Walt Kienzle 1991 9000T "pablo" <pabloNnopsamsimplyhombre.net> wrote in message news:RrP1a.1651$YH4.63850801nopsamsvr15.news.prodigy.com... > > Could anyone tell me where to find information about the "AON" method Saab > seems to use when talking about fuel grade requirements? A sticker in my car > claims I need to use 93 AON, but in California it's (R+M)/2 everywhere, and > one can only find 91 grade as premium fuel anyway. The question is - are AON > and (R+M)/2 significantly different, and is the fact we are forced to use 91 > grade here in CA negatively affecting performance and engine integrity of > our Saabs? > > ...pablo > >