Confusing Octanes
Posted: Wed Jun 04, 2008 8:08 amThis was in this months Car and Driver Magazine ( JUL 08 )
Q: Regular gas in North America is 89 octane and premium is 93 octane. In Europe, "regular" is 95 octane and premium is 98. (In Germany, premium also runs 100 octane.) How come a car requiring premium gas in Europe can run on North America's 93 octane premium gas?
A: North American and European octane ratings use a different scale in the same way 30 degrees is really hot in the EU but pretty chilly in the U.S.A. The octane rating is a relative measure of a fuel's resistance to detonation-in the case of a gasoline engine, we're talking about knock. The octane rating comes from a standardized laboratory procedure. In Europe they use the Research Octane Number (RON). In North America we include the Motor Octane Number (MON) and average it with the RON; if you read the fine print on an octane label you'll see this referred to as the (R+M)/2 method. The MON is significantly lower then its comparable RON rating, and that's why American numbers are lower. In general, 91 RON is equivalent to 87 (R+M)/2, 95 RON matches with 91 (R+M)/2, and 98 RON is effectively 93 (R+M)/2 fuel.
...just a little trivia for ya...
Q: Regular gas in North America is 89 octane and premium is 93 octane. In Europe, "regular" is 95 octane and premium is 98. (In Germany, premium also runs 100 octane.) How come a car requiring premium gas in Europe can run on North America's 93 octane premium gas?
A: North American and European octane ratings use a different scale in the same way 30 degrees is really hot in the EU but pretty chilly in the U.S.A. The octane rating is a relative measure of a fuel's resistance to detonation-in the case of a gasoline engine, we're talking about knock. The octane rating comes from a standardized laboratory procedure. In Europe they use the Research Octane Number (RON). In North America we include the Motor Octane Number (MON) and average it with the RON; if you read the fine print on an octane label you'll see this referred to as the (R+M)/2 method. The MON is significantly lower then its comparable RON rating, and that's why American numbers are lower. In general, 91 RON is equivalent to 87 (R+M)/2, 95 RON matches with 91 (R+M)/2, and 98 RON is effectively 93 (R+M)/2 fuel.
...just a little trivia for ya...