A few facts need to be realised.
- Octane rating indicates the ability of the fuel to resist knocking,or,pre-ignition,under high compression. The higher the rating the less likely pre-ignition will occur under most driving conditions.
- There is absolutely no relation between the octane rating & the power an engine will attain. Power is dependant on the chemistry of the fuel,more specifically it's calorific value.
- Unless the engine is both constructed & tuned to take advantage of high octane fuel it is wasted. In general terms high octane fuel is used for high compression engines.
- There are two ways of rating octane ratios. The Research method,abbreviated as RON,is the common way of rating a fuel. RON indicates the ability of the fuel to resist knocking under low engine revolutions. The Motor Octane Rating measures the fuel's ability to resist knocking under high engine revolutions. Both Ron & Mon are measured on all gasoline fuels.
- You are wasting your money on Avgas which is designed for use in piston engined aircraft which run at low & constant revolutions. It can be used in cars but why bother unless you are stealing it from your employer ?
It was used in the past for old engines which required lead fuel additive.
6. It's probably wise to accept the fuel recommendations of the car's manufacturer but the reality is that regular gasolione usually suffices since the ECU will adjust the timing via the knock sensors. The power developed by the engine will be the same. After all,road cars are tuned for easy driveability,not performance, so discussion around the relative merits of different brands of fuel is futile. However,you have a more important consideration on fuel branding. What you buy at say,a Shell station is not always Shell fuel. Fuel at a station is often bought from another refinery due to distribution difficulties or cost considerations and the mix is further complicated since a lot of fuel is imported from overseas by all companies to augment their supply chain. So what you buy as Shell may have come from a Mobil refinery mixed with imported fuel from China. And,you'll never know the difference !
When you remove all the gimmickry & sales bulls*it from fuels there's little justification for not buying the fuel closest to home at the lowest price,the car will cope just the same.