"Put a tiger in your tank, " says a classic advertising
tagline. In today’s motoring world, what kind of fuel grade
will have the power to place a beast in your fuel tank?
The answer, according to experts who study fuel efficiency
in detail, is both regular and premium petrol. And it would
be a waste of money to favor premium over regular,
especially in these times when petrol prices are high,
according to the experts.
Virtually nothing is gained by filling up with a premium or
more expensive grade of fuel than the vehicle manufacturer
has recommended, the experts say. And many of the same
experts explain that drivers may not lose much performance
from their cars by using a lower grade of fuel than
recommended by the car manufacturer.
There is little difference in energy content of regular versus
premium petrol. They both contain about 111, 400 British Thermal Units
of energy per gallon.
The price difference, however, between the fuel grades is anywhere from
20 cents to 40 cents, depending on where you live in the country. The experts’ consensus goes against the long-held
belief by thousand of drivers who fill up with premium only,
or on every third or fourth trip to the pump. The idea is to
fill up with premium every so often to clean out the engines
or rev up the performance of older engines.
But according to the experts, this practice is like tossing
quarters in a wishing well, since most engines are designed
to operate on relatively low-octane regular unleaded petrol.
Octane is defined as a fuel’s resistance to knocking. There
is no benefit if the octane is higher than what the engine
needs. Engine knock occurs when fuel in a combustion chamber
ignites before it should. This disrupts the engine’s
operation. But electronic knock sensors are now common and
have nearly eliminated engine disruption.
The American Petroleum Institute says if you find that your
car runs fine on a lower grade, there is no sense switching
to premium. The Institute recommends following
manufacturer’s recommendation, but even those manufacturers
say that it is more of a suggestion than a command.