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Since it's been discussed in the "Anyone do any Mods yet?" thread, I was curious to see what type of gas you use in your Impreza?
 

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Since it's been discussed in the "Anyone do any Mods yet?" thread, I was curious to see what type of gas you use in your Impreza?
The car is rated for regular unleaded, but if you feel like dumping a couple extra dollars using premium won't hurt. I had a 4th gen impreza with uel header swap and custom cat back that ran smoother and cleaner with the premium gas
 

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Unless it calls for something with more octane, I run regular.

That being said, if given the opportunity, I like filling up with the old school, ethanol free stuff. It's more expensive than ethanol blend but I've noticed about 10% gains in fuel economy and my "butt dyno" registers a bit more power.

Ethanol free is all the only gas I run in our dirt bikes, UTV, mowers, trimmers and chainsaws. Not only do they run better but the fuel stays fresh longer, which is important for winter storage.
 

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Unless it calls for something with more octane, I run regular.

That being said, if given the opportunity, I like filling up with the old school, ethanol free stuff. It's more expensive than ethanol blend but I've noticed about 10% gains in fuel economy and my "butt dyno" registers a bit more power.

Ethanol free is all the only gas I run in our dirt bikes, UTV, mowers, trimmers and chainsaws. Not only do they run better but the fuel stays fresh longer, which is important for winter storage.

Where would one find ethanol free gas? Is the pump a different color like diesel or E85?
 

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Where would one find ethanol free gas? Is the pump a different color like diesel or E85?
Not necessarily a different color. The mom and pop gas station where I buy mine just advertises it directly on the pump. One pump is dedicated to non ethanol and the two adjacent pumps are either regular 10% or diesel.

It's not something that you'll typically find at just any local gas station. Depending on where you live, you might even have to search high and low until you find some. Since there is a lot of logging activity here, lumber companies like to buy it in bulk for their operations.

You might have luck calling fuel distributors directly to see which gas stations they deliver non-ethanol to.

It's not often that I can fill up my truck or cars with it. The closest station to me that sells it is still over 50 miles away and happens to be on the way to our cabin. So, logistically it proves difficult to run all the time. Instead, I carry 5 gallon jugs as needed and keep my off road vehicles and power equipment topped off.

You might even find that the hassle isn't worth the effort. If non ethanol costs more than 10% premium gas and you're only gaining a few miles more per gallon, then you won't be coming out ahead financially. I primarily keep it on hand for long term storage first and power gains second. Fuel economy isn't a primary factor for me.
 

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87 here, haven't developed the will to spend the extra bucks on plus or premium. Regular in NY is 2.33 or so a gallon.
For me it's nice to use regular for once as my last car was a turbo that required a higher octane.
 

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Ever since I learned that using anything more than whats recommended is a waste I always use regular. Even in some cars that called for premium I went regular. This generation Impreza will be no different for me unless I get aggressive with modifications. Apparently some tunes prefer you use premium.
 

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If you are running a boosted car(supercharged.turbocharged )yeah premium gas would be good
In the Impreza I use Shell 89 octane 5% ethanol
 

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I've been doing the Calculations and stuff.. My first tank was 87 regular. Current tank is 87 Ethanol free. My next tank will be premium. I prefer to see mpg and smoothness at this point. No real mods, no real reason to go crazy with premium all the time.
 

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Discussion Starter #10
Interesting replies. With using say premium gas for instance, you hear about hearing a "knocking" sound. Is anyone worried about this occurring? Just curious. My last car, 4G Eclipse, recommended regular, but since I modded the CAI, headers, exhaust, etc, I ran premium & felt it had way more power & got better mileage.
 

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There is no reason to use anything but regular 87 octane in this car, unless:

- you have engine mods which call for it (mostly more aggressive timing)
- you don't want to use gas with ethanol in it - where I live the only way to do that is to buy premium from certain gas stations. As someone else mentioned this is the gas I buy for lawn equipment / generators as it keeps longer
- your engine is not running smoothly on regular; but really you should be taking it to the dealer to be looked at in this case
- you have too much money and want to give some of it to the oil companies

Higher octane gas actually has less energy per unit, so unless your engine is specifically designed to run on it the chances of you getting better mileage is extremely slim / all in your head.
 

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Interesting replies. With using say premium gas for instance, you hear about hearing a "knocking" sound. Is anyone worried about this occurring? Just curious. My last car, 4G Eclipse, recommended regular, but since I modded the CAI, headers, exhaust, etc, I ran premium & felt it had way more power & got better mileage.

Before we met, my wife ran exclusively 87 octane in her supercharged Xterra despite Nissan recommending higher. It's now 15 years old and still running fine.

Modern cars utilize knock sensors to "listen" for detonation (engine knock or pinging) and adjust the timing accordingly. Provided that you haven't heavily modded your car to the point where retarding the timing no longer protects the engine, then you can probably get away with the cheap stuff. However, there will be a performance and efficiency hit unless you run the higher octane fuel.

Put it this way, it will "run" on 87 octane. But it *runs* on premium.
 

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I'm not from the US, so I have a japanese made Impreza, the manual here recommends 95 RON (~90 on US/AKI), so I use that.
It would be interesting to know if there is any difference on the engine for different markets
 

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The Australian models have 95 RON as recommended, but 91 RON as minimum. I've been using 95+, but has anyone in Aus tried the E10 94 stuff? Its cheaper here and arguably more environmentally friendly.
 

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If you live in the US, anything more than 87 is a BIG waste of your hard earned money. There are 100's of studies that show putting anything more than 87 in a car that calls for 87 from the manufacturer does absolutely nothing...zilch...nada for your car other than suck additional funds out of your wallet. @Pointy_End summed it up well. There is nothing you can do to these cars that would require anything more than 87. If you "think" your car feels better at 89, 91 or 93...it's the placebo effect and your mind is only trying to justify the tank of gas you just way over paid for:wink2:
 

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Higher octane isn't better, but if you run a high compression/boosted engine it may be required.

Your N/A Impreza wants the "cheap" stuff so take advantage of that and feed it the "cheap" stuff.
 

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had my first fill up of 91 before my oil change a few days ago and i will admit, the car does idle MUCH smoother and the power is much more linear and the car is eager to respond to full throttle. not saying ive seen power gains but it seems like it merely because everything is much smoother than 87 and i feel like at higher speeds its still willing to pull, but that could just be my butt dyno, i dunno. if you have the extra change to shell over, i would personally say its worth it.

edit: i also noticed the car idled like garbage the minute i filled up with 91 so i mustve been using some horrible 87 beforehand.
 
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