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To Octane or not to Octane

   Ducati figured out your engine's octane needs using knock sensors during engine development on a dyno. So, if you haven't changed compression ratio, it is best to follow the factory's recommended fuel octane rating listed in your Owner's Manual. Each variation of the venerable v-twin has a different requirement depending upon the state of tune from the factory. For example, in a 916 they recommend US Regular grade fuel but they recommend either US Plus (which is better if it doesn't ping) or US Premium grade in a 998. Pay attention to the rating system specified in the manual.
   For Ducatis, the owners handbook will specify the minimum fuel octane requirement as either 92 RON (the same as US Regular 87 octane), 95 RON (US Plus), or 98 RON (US Premium.) The octane rating (where the R in the US equation is Research and the M is Motor) system is different in the US. When this system is used, 87 (R+M/2) is called Regular, 89 (R+M/2) is called Plus and 92 (R+M/2) is called Premium. A lot of US owners have made the mistake of using Premium after seeing 92 octane specified in the Manual.

US

Europe

RON MON (RON+MON)/2
Unleaded 87 Normal 91
91
82.5
86.75
Plus 89 Euro Super 95
95
85
90
Premium 91 to 94 Super Plus 98
98
88
93
A sample of factory recommended fuel ratings
2002-2005 Multistrada 1000DS95-98 RON
2002 99895-98 RON
2001-2002 748R95-98 RON
2001-2002 Monster S495-98 RON
2001 Monster 60095-98 RON

And for your further reading pleasure....

What does Octane Mean?
   By Marshall Brain
Sourced from howstuffworks.com, the original article can be found here

   If you've read How Car Engines Work, you know that almost all cars use four-stroke gasoline engines. One of the strokes is the compression stroke, where the engine compresses a cylinder-full of air and gas into a much smaller volume before igniting it with a spark plug. The amount of compression is called the compression ratio of the engine. A typical engine might have a compression ratio of 8-to-1. (See How Car Engines Work for details.)
   The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. When gas ignites by compression rather than because of the spark from the spark plug, it causes knocking in the engine. Knocking can damage an engine, so it is not something you want to have happening. Lower-octane gas (like "regular" 87-octane gasoline) can handle the least amount of compression before igniting.
   The compression ratio of your engine determines the octane rating of the gas you must use in the car. One way to increase the horsepower of an engine of a given displacement is to increase its compression ratio. So a "high-performance engine" has a higher compression ratio and requires higher-octane fuel. The advantage of a high compression ratio is that it gives your engine a higher horsepower rating for a given engine weight -- that is what makes the engine "high performance." The disadvantage is that the gasoline for your engine costs more.
   The name "octane" comes from the following fact: When you take crude oil and "crack" it in a refinery, you end up getting hydrocarbon chains of different lengths. These different chain lengths can then be separated from each other and blended to form different fuels. For example, you may have heard of methane, propane and butane. All three of them are hydrocarbons. Methane has just a single carbon atom. Propane has three carbon atoms chained together. Butane has four carbon atoms chained together. Pentane has five, hexane has six, heptane has seven and octane has eight carbons chained together.
   It turns out that heptane handles compression very poorly. Compress it just a little and it ignites spontaneously. Octane handles compression very well -- you can compress it a lot and nothing happens. Eighty-seven-octane gasoline is gasoline that contains 87-percent octane and 13-percent heptane (or some other combination of fuels that has the same performance of the 87/13 combination of octane/heptane). It spontaneously ignites at a given compression level, and can only be used in engines that do not exceed that compression ratio.
   During WWI, it was discovered that you can add a chemical called tetraethyl lead (TEL) to gasoline and significantly improve its octane rating above the octane/heptane combination. Cheaper grades of gasoline could be made usable by adding TEL. This led to the widespread use of "ethyl" or "leaded" gasoline. Unfortunately, the side effects of adding lead to gasoline are:
      * Lead clogs a catalytic converter and renders it inoperable within minutes.
      * The Earth became covered in a thin layer of lead, and lead is toxic to many living things (including humans).
   When lead was banned, gasoline got more expensive because refineries could not boost the octane ratings of cheaper grades any more. Airplanes are still allowed to use leaded gasoline (known as AvGas), and octane ratings of 100 or more are commonly used in super-high-performance piston airplane engines. In the case of AvGas, 100 is the gasoline's performance rating, not the percentage of actual octane in the gas. The addition of TEL boosts the compression level of the gasoline -- it doesn't add more octane.
   Currently engineers are trying to develop airplane engines that can use unleaded gasoline. Jet engines burn kerosene, by the way.

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