Does Oppo Premium Fuel?

"LimitedTimeOnly @ opposite-lock.com" (limitedtimeonly) 10/26/2019 at 20:25 • Filed to: I want to be an Overlander but let's get real, premium gas

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So, !!!error: Indecipherable SUB-paragraph formatting!!! . It’s !!!error: Indecipherable SUB-paragraph formatting!!! , but !!!error: Indecipherable SUB-paragraph formatting!!! and she’ll just use whichever I’m not using. Whatever, here is the critical question: Should I dictate that premium fuel be used?

It is a 2020 Subaru Outback with the 2.4L turbo engine. From very brief internet research, it is supposed to run on regular, low octane gasoline. However, given that it is a direct injection turbo engine, would I be protecting it by using high octane (93) gasoline?

On my GTI with the 2.0L turbo, I only use premium, both for this reason and to get the most power.

In the end, it might be easiest to say that both of “my” cars get premium to keep it simple for my wife, but I’m curious if anyone has particular knowledge in this area.

ranwhenparked > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 20:42

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No, my car does not require it. I do, however, go out of my way to buy ethanol-free gas whenever I can  find it.

Nick Has an Exocet > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 20:44

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I do in the car that requires it (Lancer Ralliart) and don’t in the Miata. I do however, put premium in the Exocet. It doesn’t need it, but it gets run at such RPM so often that it can’t hurt.

VW Max > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 20:45

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Shouldn’t you use whatever the owner’s manual/fuel cap label recommends ?

LimitedTimeOnly @ opposite-lock.com > Nick Has an Exocet 10/26/2019 at 20:48

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I can’t remember if my GTI calls for premium  . . . I think the 2015 did, but my 2016 somehow did not. I exercise it enough that it seems like a worthwhile investment . . . but the Outback probably won’t see that kind of treatment, especially with a CVT keeping the revs steady.

LimitedTimeOnly @ opposite-lock.com > VW Max 10/26/2019 at 20:50

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Probably. I am just wondering if there is any argument for premium fuel being more mechanically beneficial for direct injection and/or turbo than regular, even if that is acceptable.

Dr. Zoidberg - RIP Oppo > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 20:50

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I do what the filler cap tells me to do

If only EssExTee could be so grossly incandescent > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 20:51

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If your car doesn’t specifically call for it, there is NO BENEFIT to using premium. Cars that need premium will adapt to run on lower o ctane gas but not vice-versa..

Pixel > If only EssExTee could be so grossly incandescent 10/26/2019 at 20:56

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This. It is purely a waste of money in a car that doesn’t need it. The only time my car gets premium is when i am putting the “fun” car away for the winter. Because higher octane means even if the fuel degrades some it will still have enough octane to work come spring.

Nick Has an Exocet > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 20:59

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I t’s usually way more of a concern for turbo cars since they are running boost / more sensitive to knock. Fifth Gear did an interest test on the GTI a while back but all it really tells you is that they year of the car they had was optimized for premium and pulled timing or boost with low octane. If the ECU had been developed for low octane and didn’t have different programming for making use of high octane, there would be no difference. 

WilliamsSW > If only EssExTee could be so grossly incandescent 10/26/2019 at 21:02

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^^^^^^^^ x100

Bylan - Hoarder of LS400's > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:06

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Use whatever fuel the manufacturer tells you to use.

To get into the actual nitty gritty of it, there is no difference in “quality” from “regular” 87 octane fuel vs 91 octane “premium” fuel. Honestly the names are complete nonsense. A higher octane fuel resists combustion, a lower octane burns easier . So, 91 fuel req uires more energy and engine compression in order to combust. This is why performance cars, and usually turbo-charged engines, require premium fuel, and your average mommy-van does not. Putting lower octane fuel in a car that requires premium will result in engine knock and pre- detonation, because the fuel is combusting too easily and too soon. This damages engines, and wastes a lot of fuel, and kills HP . Putting premium fuel into a car that was made to run on 87 is a waste of money, and is forcing the engine to ignite something it doesn’t have the compression and spark to properly ignite. I’m not a pro, but I’ve researched the idea a bit and learned about what fuel octane actually means.

You cannot go wrong putting the fuel your m anufacturer tells you to put in, you can go wrong by thinking they are fools and thinking you’re putting “better” fuel in your car. I am rather surprised that the 2.4l Turbo Subaru engine doesn’t require premium fuel, but they built it and tested it and probably do know why.

LimitedTimeOnly @ opposite-lock.com > If only EssExTee could be so grossly incandescent 10/26/2019 at 21:06

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https://www.edmunds.com/volkswagen/gti/2010/long-term-road-test/2010-volkswagen-gti-the-effect-of-octane-on-its-power.html

Maybe not NO benefit, but pretty close.

wafflesnfalafel > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:07

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yep - I tried mid grade once and the WRX ran like sh!t.  Honestly, I wish I had easier access to some of the higher test fuels...

slipperysallylikespenguins > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:07

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I put regular in all my cars and premium in my bikes. The bikes don’t call for it but it doesn’t cost much more when you are only filling 4 gallons.

If only EssExTee could be so grossly incandescent > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:09

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The car used in that article  requires premium.

Supreme Chancellor and Glorious Leader SaveTheIntegras > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:10

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Acura calls for 91 in the TLX, so it gets 93...cause you don’t find 91 in NJ

facw > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:17

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Volvo recommends 91, so I fill up with 93 (no weird stations around here selling 91).

JawzX2, Boost Addict. 1.6t, 2.7tt, 4.2t > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:18

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Part of the entire magic of DI (t urbo) e ngines is that the ability to control the exact time that fuel is introduced into the compression cycle (via direct injection) allows the engine to prevent detonation by not even having fuel present in the combustion chamber until an explosion is desired. This almost co mpe tely eliminates incidence of pre-ignition (eg: pinging or detonation), which is a primary argument for use of higher octane fuels in high-compression (turbo) engines. If a good quality, clean gasoline is used a (properly functioning) DI Turbo engine is in no mechanical danger from running lower octane fuels. HO WEVER, most DI engines, especially turbo-charged ones, will produce more power on higher octane fuels. Our Hyundai Kona with the 1.6tgdi engine and the seven speed dct gets a power boost that improves it’s fuel economy enough to make filling it with non-ethanol 93 octane a financially sound prospect, however our Ford F150 with the 2.7 ecoboost (second gen with both DI and port injection) doesn't benefit enough (with the factory fueling program) to make putting anything other than 87 octane in it worth the money... Now if we were to put a tune on the F150, that 2.7ecoboost can put out some serious power numbers running on 93 (or better yet, 100) octane, just not the way the factory ecu program does things.

BrianGriffin thinks “reliable” is just a state of mind > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:20

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I’ve done literally no research on the new 2.4l turbo. I’ve had small turbos on some cars (VW 1.8t) where running premium made no different - and that makes sense, it’s spec’ed to regular. Right now I have a 535i that requires at least 91, and is happier with 93. I also have a LR4 that “recommends” 91 but is fine, though a bit more sluggish, on 87.

Use what Subaru recommends and you’ll be fine. BUT! I bet you can tune it and get tons more power on 93. 

Demon-Xanth knows how to operate a street. > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:22

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My 2004 Grand Prix GTP liked 93, my 06 Ram 89. Everything else 87, higher gives no benefit.

DipodomysDeserti > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:37

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If it’s tuned for low octane, then putting higher in won’t help anything. Timing/boost/fueling is already adjusted for the lower rating. 

Where have all the lightweights gone? > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 21:47

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My owner’s manual (2016 Chevy SS) says use premium fuel, so I do.

LimitedTimeOnly @ opposite-lock.com > If only EssExTee could be so grossly incandescent 10/26/2019 at 21:47

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Huh. Good catch.

DasWauto > wafflesnfalafel 10/26/2019 at 21:54

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The WRX requires premium - t he owner’s manual says it can run on 87 if there’s no other option but it will indeed run poorly. The new Outback XT only requires regular gas, premium is not necessary or beneficial to the health of the engine.

LimitedTimeOnly @ opposite-lock.com > Bylan - Hoarder of LS400's 10/26/2019 at 22:00

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I’ll see what the Outback owner’s manual says once I actually have the car.

I just checked the GTI manual, and that says follow the rec on the filler cap, which says 87. It does emphasize using tier 1 suppliers to have the best detergent additives.

I guess I got convinced by internet wisdom in 2016 that 93 might have benefits, and would have no drawbacks.

415s30 W123TSXWaggoIIIIIIo ( •_•))°) > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 22:01

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I do in my Acura, it calls for it, just use what octane it calls for.

ADabOfOppo; Gone Plaid (Instructables Can Be Confusable) > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 22:07

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The GTI does not -require- premium, but reading the manual about fuel economy figures they have their little *Figures achieved using premium gas disclaimer.

Not sure what Subaru has to say about using premium. Do you have 89-octane available? Split the difference?  Or a Costco and just get 93 for the same price as mid-grade?

LimitedTimeOnly @ opposite-lock.com > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 22:11

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Looking at old forum posts, I see that the 2015 GTI required 91 octane, then they did change something for 2016 to permit 87 octane. I think that this made me inclined to stay higher octane, thinking that this was just to permit use of 87, but that the engine really preferred 91 (or higher).

I think I’ll likely stick with high octane for the GTI for this reason, but follow the manufacturer’s recommendation for the Outback.

LimitedTimeOnly @ opposite-lock.com > ADabOfOppo; Gone Plaid (Instructables Can Be Confusable) 10/26/2019 at 22:21

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I’m willing to spend on premium fuel, if it makes any mechanical or performance difference. I will look for any indication of performance difference in the Subaru manual once I get it.

wafflesnfalafel > DasWauto 10/26/2019 at 22:25

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uh... yes, I guess, by the book. Though that isn’t necessarily where the motor is happiest...

The NA motors are rated on 87, and work pretty well on that fuel.  The turbos will take it, but just are not as happy.

PowderHound > LimitedTimeOnly @ opposite-lock.com 10/26/2019 at 23:44

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Yes, Mine is tuned for 93.

ITA97, now with more Jag @ opposite-lock.com > LimitedTimeOnly @ opposite-lock.com 10/27/2019 at 07:35

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I run premium only in my F-150/2.7 Ecoboost. Ford tells you it can run on 87, but requires 91 for use when towing/hauling. There is a pretty consistent 1mpg loss when I’ve run 87, and there is a notic able difference in the ignition/boosting strategy the ECU employs.  Lighter loaded/low throttle transitory conditions are where it seems most noticably less responsive.  

DasWauto > wafflesnfalafel 10/27/2019 at 14:40

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Have you driven anything with the new FA24? It’s pretty lovely actually and is different than the 2.ol we have, it’s not as high strung . It runs perfectly well on 87 because that’s what it was designed to run.

wafflesnfalafel > DasWauto 10/27/2019 at 20:47

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yep - drove a new Ascent. Looking forward to the “STI”ified version. If they can make 260 on a conservative tune with 87 they ought be able to get 345 for the STI with a hotter tune and premium fuel. And totally agree - it’s quite a bit more easy going than the “rambunctious” 2.0 FA in the current WRX.

CarsofFortLangley - Oppo Forever > LimitedTimeOnly @ opposite-lock.com 10/28/2019 at 12:28

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94 Ethanol Free - Fiesta ST

89 Octane - Sportwagen

89 Ethanol Free - Dodge D100

87 “Regular” - Kia Forte

DasWauto > wafflesnfalafel 10/28/2019 at 15:54

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Agreed on the STI, I’m hoping with different cam profiles, a bigger turbo, premium fuel and maybe a bit higher compression they’ll be in the 325-350hp range.

I think what I want more though is either an new WRX/STI hatchback or Crosstrek XT, ideally both. I really liked the new outback XT I drove  but prefer the size of the Impreza.