Older pre-1990 engines will run quite happily on standard 91 octane fuels, with the exception of certain models requiring super leaded equivalent of 97.
These high-performance engines have compression levels exceeding 10.1:1 that once called exclusively for premium fuels, yet today’s manufacturers are specifying a minimum RON of just 91 for power plants with the same high ratings.
The reason they can do this is Variable Valve Timing (VVT).
VVT combined with sophisticated engine management systems physically adjusts internal compression pressures through advancing or delaying the opening of the engines intake and exhaust valves and spark control.
Under acceleration, an engine’s valve events are delayed while under low throttle cruise they are advanced or held open for longer.
It’s through this type of technology that vehicle manufacturers are able to harness higher performance and fuel economy out of today’s engines while using lower-grade fuel.
So, are premium fuels right for everyone?
With the exception of turbocharged/supercharged models or models specifically recommended by the manufacturer, then the answer is generally no.
Engines in today’s cars are nothing like they were 20 years ago – they're far better.
Today’s engines are designed with high levels of efficiency and performance in mind and as a result of VVT technology, today’s highly stressed units are able to thrive on lower grades of fuel as a result.
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