Will it hurt to run regular gas in a Subaru WRX with turbo?

Answer 1

Probably. Most regular gas has an octane rating of about 87. This adequate for an American V-8 engine, but not for a high performance engine. Prior to the introduction of unleaded gas, Regular was usually about 92 octane, and Supreme was between 95 and 98 octane. To get what used to be Regular gas, you have to buy Supreme now. I disagree. The answer is yes or no, depending upon whether Subaru uses a knock sensor on this engine. The knock sensor will modify the timing of the ignition to adjust for regular gas. You would then lose a little horsepower and mileage in exchange for the ability to use the cheaper gas. You can research this, or find an old school mechanic who can hear pinging or preignition, put a gallon of regular into your WRX empty gas tank. If it pings, fill the tank with premium and don't use regular, if it doesn't ping, use whatever gas gives you the price - mileage - performance compromise you want. You can mix portions of tankfuls and the knock sensor will provide an intermediate timing solution.