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I'm everyone's been asked this question at least once. But seeing as how most engines made in the past decade are engineered to take both even though a lot of them recommend using only premium. So whats your 2 cents about about this topic?
 

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I'm thinking it'll be Premium only. Even with direct injection 12.5:1 compression is insane. For comparison, WRC cars are regulated to run at 12.5. So I don't think this engine will like cheap gas.
 

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Just go with whatever the manufacturer recommends. They always have actual data to back up their recommendation. Its not like they have a stake in the gas companies. If that was the case then every manufacturer would only recommend premium.
 

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Due to 12.5:1 compression ratio. Its a given premium (at least 91 octane) fuel will be a requirement for optimum performance in the BRZ. Myself I will run Chevron 94 octane, I have always been happy with chevrons fuel. :) Of course, since the inception of fuel injection, as a fail safe, you could run regular or mid grade if your cheap, you just get severely retarded ignition timing and terrible performance.
 

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I would just use premium. Not because people say you get better mileage. Not because people say it makes it run faster. But mainly because most premium gases don't have ethanol mixed in. Also premium gases can remain stable in your tank way longer than regular gas. Meaning if ever for some reason you're unable to start it up for a long time it wont gunk up the fuel lines.
 

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Premium. I've heard statements all over the place from 25-35mpg. It depends how you calculate it apparently. NO idea. I don't think the BRZ or FR-S will be bad on gas. And it wasn't a concern anyways.
 

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Preumium! 91 or 89 for sure!

but id def say 91, just due to the high compression motor, any lower of an octane grade it might knock.
 

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Just like every recent car sold that "requires" premium, you can get away with lower octane fuel, as the OEM assumes stupid people will try to cheap out and pump 87 octane to save a few pennies in the short term. Putting lower-than-recommended octane means you're banging off the knock sensor more than typical, so piston ring lands will wear quicker, fuel economy and power will both suffer. If the OEM recommends premium gas, and you're not an automotive engine designer, don't get creative and think you're smarter than the designers.
 

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it say in our dealership PoP that it will require 89+

its direct injection, everything is so precise in the cylinder, would want to mess that up.
 

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kind of hard to get 93 octane... at normal places so cheapening out would to get the 91 octane, if you really wanna push your luck and pump 87 or 89 I'm sure you'll notice the difference in performance as well as engine knocks and who knows what other kind of problems
 

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kind of hard to get 93 octane... at normal places so cheapening out would to get the 91 octane, if you really wanna push your luck and pump 87 or 89 I'm sure you'll notice the difference in performance as well as engine knocks and who knows what other kind of problems
You will never hear a modern engine knock by using a lower octane fuel. A knock sensor will pick this up immediately and severely reduce ignition timing and therefore reduce engine performance. But, nowadays you will never see engine damage, only the car would be really terrible to drive being out of its optimum operating characteristics.
 

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Direct quote from the manual.

Octane rating: 93 AKI or higher *

* = If unleaded gasoline with an octane rating of 93 AKI (98 RON) is not available,
unleaded gasoline with an octane rating of 91 AKI (95 RON) may be
used with no detriment to engine durability or driveability.
 
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