Now that petrol prices are so high, who can afford to buy “premium” or “high-spec” petrol any more? But does premium petrol provide any benefits in the first place, and is regular petrol “low grade”? In Malaysia, regular petrol is sold at 2.62/liter, premium at RM2.70/liter, while high-spec petrol such as Shell V-power goes for RM3.00/liter or more.
The bottom line is, unless your car manual specifically mentions it, there is no need to use premium petrol. And regular car engines do not benefit from it. Even cars like Porsches will still run fine on regular petrol (see the USA Today article below).
Cecil Adams, who writes “The Straight Dope” column, tackled this issue as far back as 2004:
What's the difference between premium and regular gas?
A USA Today article from 2003 also covered this ground. The writer quotes oil company engineers and technical experts from car companies:
Why use premium gas when regular will do?
More recently, a Scientific American article from Jan 2007 provides the last word on this topic:
Fact or Fiction? Premium Gasoline Delivers Premium Benefits to Your Car
The sub-heading is: “Exploding the myth that premium gasoline delivers better performance in the average automobile”. The writer quotes a mechanical engineer at the California Institute of Technology, and a chemist at the Massachusetts Institute of Technology
Here are the best quotes from these three articles:
“Using high-octane gas in a car designed for regular accomplishes little except more rapid combustion of your money.” - Cecil Adams
There is "no way of taking advantage of premium in a regular-grade car," - Bob Furey, chemist and fuels specialist at General Motors.
... for standard cars on the road today, purchasing premium gasoline is simply paying a premium for a fuel that delivers no added benefits. "If you think you need it," Green (MIT chemist) says, "you're being very eccentric."
In a related issue, my pal Riggy, who blogs about motoring, notes that higher octane petrol requires more processing at the refinery, and thus, has a higher environmental impact. Brendan I. Koerner covered this angle in Slate:
The Premium Premium: Is high-octane gas bad for the environment?