Q: Should I use Octane Boosters? A: The Evolutions are built for the Japanese home market and as such the cars would normally use 100 RON fuel. The maximum rated fuel that is obtainable from filling stations in the UK (and most of the EU) is currently 98 RON (Shell Optimax) or 97 RON (Super Unleaded). Using a lower RON rated fuel than was intended by the manufacturer means the engine will not be running at it’s maximum potential and if the RON rating is too low it can actually be harmful (generally don’t use fuel rated less than 97 RON unless in an emergency, see ‘What is the best fuel to use?’). You can use an Octane Booster to increase the fuels Octane Rating to 100 RON (or more). Many people do use Octane Boosters, especially when using their cars on track days, then again just as many do not use them, it is entirely up to the owner whether they feel it is worthwhile. The official line is not to use Octane Boosters, even in an emergency. Also note that your warranty maybe affected if you do use an Octane Booster. It has been said, rightly or wrongly, that Octane Boosters can actually leave traces of their use in the engine and fuel system and if you have an engine failure, a warranty claim may not be met if their use is evident. Back to question page