Well I did a search on fuel and could not find too much on the topic. This discussion was also raised at 400thumpers.com Shell in Oz have a fuel called 'Optimax' which is a High Density High Octane unleaded fuel. This fuel is basically a higher mass of fuel that is packed into the same volume. A tank of this actually weighs more than a tank of premium unleaded and therefore has more fuel available for combustion,supposedly resulting in better fuel economy. Shell claims that it vapourises and ignites more readily and burns more completely. This improvement translates directly to a more efficient combustion, the most tangible result I've noticed being a more responsive engine. I guess the high octane is perhaps the most obvious performance enhancement as it has a 98 RON .I think most other Premium unleaded fuels typically rate at 95 RON dependent upon the manufacturer and state controls. I use it in my bike and don't have any problems.. in fact it runs great, never fouls plugs and seems to help in delivering a nice crisp throttle response. I'm just curious to see what fuel other WR owners are running and what possible effects (if any) different fuels have caused in your bike? How much does petrol differ internationally? I've also ran super (which is leaded) and regular unleaded. I noticed nothing radcially different in the response of the bike, except that the Shell Optimax seemed rev a bit cleaner and there seemed to be less carbon build up around the end of the muffler? The sticker on the tank said unleaded fuel only..I'd say this is to comply with ADR (road compliance) but are there any ramifications of running anything else? Curt.