Is Premium Fuel Really Necessary?

I have a Mazda CX-7 and it requires premium gas – is it necessary all the time? Or what are the consequences if it was bought used and it wasn’t put premium all the time?

Mazda CX-7s are mostly equipped with a turbo-charged engine.

This family of engines, develops more horsepower than a comparable, naturally aspirated engine and it does so by raising the volume of air in the cylinder. The higher pressures and temperatures that result, produce the extra power. However, as temperatures rise, the mixture can self-ignite with the familiar “pinging” sound. This spontaneous combustion can cause severe mechanical damage to the engine. Premium fuel has a higher octane ratings which allow higher temperatures (and thus more power) without the dreaded knocking and consequential damages.

As protection, manufacturers have added a device called a Knock Sensor to monitor the undesirable engine knock and allow the engine computer to retard the spark timing when pinging is detected. Retarding the spark while saving the engine, has a negative impact on engine performance and fuel consumption efficiency.

Ultimately, the verdict of which fuel to use can be found in the owner’s manual. If it says “Premium fuel is recommended” then that is the correct choice. It might hurt to pay $1.42 per litre but you will get most of it back in improved fuel mileage.

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