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::..Regular Gas *87 -- can you use it if you're not using a ton of boost??..::

1108 Views 9 Replies 7 Participants Last post by  rqjoe
Will using Reg 87 Gas grenade the mill, even with light, non-aggressive driving.?

Anybody using Regular Gas?

(*I do understand why premium is used in this application, just asking the question*)

I'm talking in a non-modified OEM WRX.

I'm all ears....

Thank you in advance for your answers
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You'll be just fine. Just stay out of higher boost to be on the safe side.

You were not the first, nor the last to do this.
Were you thinking of using it all of the time? That would not be a good idea ...
I would not.

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What I did not explain well is people mistakenly end up with 87 for one tank.

To do so all the time is asking for trouble.
Take it really easy and stay well out of boost. Sometimes I throw in a bottle of octane booster, but how much it helps is outside of my knowledge

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If you have to put reduced octane into the car, fill-up with the proper octane when you get to around ½ tank, three (93) or four (91) times.

First fillup: 50% proper gas
Second fillup: 75% proper gas
Third fillup: 87.5% proper gas

Your car has an active knock control strategy, so it will pull timing to prevent detonation. As a result, even after you get the majority of proper gas in the car, the vehicle may feel a bit "sluggish" while it slowly adds advance back in that it pulled due to reduced octane.
Were you thinking of using it all of the time? That would not be a good idea ...
This. Not saying that the OP is saying this, but we've had folks in the past ask about running 87 in their cars, full time, and it always confused me. You spent nearly $30K for a turbocharged enthusiast car, then want to quibble over paying $4 more per fillup? Maybe you bought the wrong car for your budget.
Keep in mind how modern cars usually work, including the Scoobies. Knock detection isn't psychic, it doesn't predict knock in advance. It detects knock as it happens THEN pulls back. So you do get some knock before the car adjusts its behavior to compensate. There is a chance that even just that little initial knock can still bone your engine. Can you run lower octane gas? Sure no problem. As long as you understand that it requires the driver to tip-toe on the gas pedal. If you can do that you'll be okay. If you drive on the highway alot and romp on the onramp to merge, or you habitually stomp on the gas to overtake alot then I wouldn't suggest it.
Don't forget the FA2.0 is a high fairly high compression engine even without the turbo boost. It could knock in certain load conditions even without boost. As most everyone has said, you could get away with low octane gas if you don't put much load on the engine (high boost or lugging at low speeds.) But it is certainly not good practice and does not follow the manufacturer's recommendations for normal use.
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