What is Octane?
Octane is a measure of a gasoline's ability to resist knock or pinging noise from an engine. Most cars require regular 87 octane fuel only, and will not get any benefit at all from using 89, 91, or 94 octane fuel.
What is Knocking or Pinging?
They are noises which are signs that the fuel and air mixture are combusting unevenly in the cylinder.
Most modern cars have knock-sensors. The knock-sensor will detect the knocking or pinging, and when necessary, will use the information to delay the spark and to minimize knocking or pinging.
Persistent engine knock, however, should not be ignored since it can result in serious damage to the engine.
Who should use high octane gas?
A few modern cars recommend or require premium (high octane) fuel. Some older sports cars and some luxury cars with high compression engines use it.
Myth: Premium is better because it does not contain ethanol.
Fact: many premium fuels these days, like Regular gas, also contain ethanol. Check the sticker on the pump.
E.g. Petro Canada: "most grades of Petro-Canada fuel may now contain up to 10% ethanol. This represents a change from the previous state, where premium fuel was ethanol-free at Petro-Canada.
What about those special detergents in premium fuel?
These days, all octane grades of all brands of gasoline sold in Canada contain enough engine cleaning detergent additives to protect against the build-up of engine deposits, standards set by the Canadian General Standards Board (CGSB).
In Canada, most major gas station retailers now sell top tier detergent gasoline in all of their octane grades, which is even higher than the standards set by the Canadian General Standards Board. All top tier gasoline has top tier level detergents in it, even the Regular gas.
The following video from toptiergas.com explains more:
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So how much detergents are enough?
Industry experts we've spoken with point out that there is a "maximum efficacy level" with detergents - after a certain point, there is no benefit to adding even more detergents to the fuel.
In fact, there could even be a potential problem with valve sticking caused from using too much detergent.
Our automotive expert Mark Whinton argues that it is a fallacy that we are driving around with "gunked up" engines that all need extra cleaning, and that today's modern engines are already fairly clean.
Even though the vast majority of the gas Canadians buy is now top tier with extra detergents and cleaning agents, Petro-Canada compares their top tier fuel to a regular fuel with only the minimum allowable level of detergents.
And although the Petro-Canada Superclean test did show a reduction in deposits on intake valves and cosmetic cleanup of fuel injectors, they did not actual do an emissions test on the fleet tested, and relied on published results with other vehicles instead.
And in this earlier SuperClean test, Petro-Canada compares their SuperClean fuel to a fuel that has <strong>no</strong> detergents at all.
As well, since new models of cars do not have indirect gasoline spraying past the intake valves, our experts argue that these types of tests on intake valves are no longer a relevant test for most modern cars.