6.16 What happens if I use the wrong octane fuel?
Description
This article is from the Gasoline FAQ, by Bruce Hamilton with numerous contributions by others.
6.16 What happens if I use the wrong octane fuel?
If you use a fuel with an octane rating below the requirement of the
engine, the management system may move the engine settings into an
area of less efficient combustion, resulting in reduced power and
reduced fuel economy. You will be losing both money and
driveability. If you use a fuel with an octane rating higher than what
the engine can use, you are just wasting money by paying for octane
that you can not utilise. The additive packages are matched to the
engines using the fuel, for example intake valve deposit control
additive concentrations may be increased in the premium octane grade.
If your vehicle does not have a knock sensor, then using a fuel with
an octane rating significantly below the octane requirement of the
engine means that the little men with hammers will gleefully pummel
your engine to pieces.
You should initially be guided by the vehicle manufacturer's
recommendations, however you can experiment, as the variations in
vehicle tolerances can mean that Octane Number Requirement for a given
vehicle model can range over 6 Octane Numbers. Caution should be used,
and remember to compensate if the conditions change, such as carrying
more people or driving in different ambient conditions. You can often
reduce the octane of the fuel you use in winter because the
temperature decrease and possible humidity changes may significantly
reduce the octane requirement of the engine.
Use the octane that provides cost-effective driveability and
performance, using anything more is waste of money, and anything less
could result in an unscheduled, expensive visit to your mechanic.
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