Im thinking of getting an outback with the 3.0 liter motor. Book saysthat it needs premium fuel, but a friend has one and he is using regular,and has been since he got the car a few years ago...What do you think? Is it OK to use regular or is premium needed...Im in San Francisco, so driving at sea level with some trips to themountains.Thanks, Joe

If the manual says premium, that's what you should use. If that's aproblem consider a different car. Yes it will run on regular but withreduced power and economy and increased possibility of detonation.

There is a penalty for using regular in an engine designed for premium. In addition there is a power loss penalty.

premium fuel for H6 3.0?

Jun 06, 2005 22 Replies

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JD 21 years ago

Only if they are tuned for regular

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Edward Hayes 21 years ago

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y_p_w 21 years ago

Aren't there different scenarios? I'd imagine that a normally aspirated higher-compression engine designed for premium would be tuned for premium at all times.

If it's a turbocharged engine, cruising at 50 MPH in 5th gear on a flat surface, it might not make that much of a difference. If there's no boost, then it's essentially a lower compression ratio engine without air being force-fed. The timing could only be advanced so far, so would the sensors detect knock with 87 (R+M)/2 octane unleaded?

Of course I'm not taking any chances. My WRX gets nothing but

91 octane Chevron Supreme.

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