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#4450574 - 07/05/17 04:07 PM Higher octane than recommended a waste?
PeterPolyol Offline


Registered: 03/06/16
Posts: 1345
Loc: toronto
On one hand, you have debunkers, skeptics and experts telling us using a higher octane/AKI fuel than the minimum sanctioned in the User Guide literature is of zero benefit, so don't waste your money. OTOH there are plenty of 'lay people' and 'non-experts' saying they've noticed a improvement in torque and response (and sometimes smoothness).

Naturally, certain people will simply add the latter group to the long list of "dumb people that are always falling for illusion and self-suggestion".

Given that, what do you believe and why?

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#4450583 - 07/05/17 04:15 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
wemay Offline


Registered: 04/04/12
Posts: 8896
Loc: Southeast Florida
Some turbos benefit (more power). In my opinion NA vehicles will not, unless they've developed a ping (my previous Sonata 2.4) and the higher octane makes it go away as a stop-gap until the car is checked out by a mechanic.
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2013 Hyundai Santa Fe Sport 2.0T
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#4450593 - 07/05/17 04:27 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
slacktide_bitog Offline


Registered: 03/20/08
Posts: 6177
Loc: USA
depends if the engine is tuned to take advantage of the extra octane, which most aren't.

You might see some benefit in flex-fuel cars, since they can run E85 which has a much higher octane rating.

A small number of cars, like the 98-02 Accord V6, don't even have a knock sensor at all

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#4450595 - 07/05/17 04:29 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
Wolf359 Offline


Registered: 04/27/12
Posts: 4766
Loc: MA
It's the placebo effect. Look it up. People think it's better, but a common layperson isn't an engineer. The BTU content of regular and super is the same. Octane is just the ability to resist knock. If their car knocked on regular, then super helps. If it didn't then it's a waste of money. Either the engine is at optimal timing or the timing is retarded. If it's at optimal timing with regular, super won't do any good.

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#4450596 - 07/05/17 04:30 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
E150GT Offline


Registered: 03/11/12
Posts: 1109
Loc: San Antonio, TX
Guess it depends on the vehicle. I have personally tried it in my current vehicles and it seems a waste of money. There may be a small gain in HP or fuel economy, but I couldn't tell. When I had a 1986 Mercedes, I could tell when my then girlfriend used the car and didnt put 93 in the tank. give it a try for yourself. Thats the only way you'll know. Thats what I did.
_________________________
1984 Mercedes-Benz 300SD - 100k
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2016 Mazda6 Touring 6MT - 56k 10w30

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#4450601 - 07/05/17 04:38 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
raytseng Offline


Registered: 12/11/08
Posts: 2342
Loc: CA
the truth is its somewhere in the middle.

likely there is a difference in a modern engine that only states regular but is still holding back a little, but it is going to be much smaller than claims. for example like 1 or 2% in hp and maybe 5% in torque.

in terms of optimization, holding back a little means it is optimally using the regular fuel and nothing is left on the table. it is not an optimization for the engine, it is an optimization of the fuel.

source: the lexus rx350 in 2012 was reclassified to use regular gas to boost sales even though it is exactly the same and not retuned. it was a pure marketting and sales move.
The engine power test numbers from Toyota datasheets decreased by the above percentage amounts with the only difference in fuel used.

you can lookup these same datasheets to see the difference of an engine that says regular and what it would get with premium run on what can be assumed is expert scientific procedures


Edited by raytseng (07/05/17 04:46 PM)

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#4450602 - 07/05/17 04:42 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
NateDN10 Offline


Registered: 01/10/10
Posts: 1735
Loc: Rochester, NY
I believe it depends on the vehicle.

On my old car, a 2005 Chevy Cobalt with port injection and 10:1 compression, there was no difference with 93 octane.
On my new car, a 2016 Mazda3 with GDI and 13:1 compression, I get about 5% better fuel economy and possibly some improvement in engine responsiveness, though that may be in my head. The fuel economy improvement, though, is real.
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#4450607 - 07/05/17 04:53 PM Re: Higher octane than recommended a waste? [Re: NateDN10]
E150GT Offline


Registered: 03/11/12
Posts: 1109
Loc: San Antonio, TX
Originally Posted By: NateDN10
I believe it depends on the vehicle.

On my old car, a 2005 Chevy Cobalt with port injection and 10:1 compression, there was no difference with 93 octane.
On my new car, a 2016 Mazda3 with GDI and 13:1 compression, I get about 5% better fuel economy and possibly some improvement in engine responsiveness, though that may be in my head. The fuel economy improvement, though, is real.

And I have tried multiple tanks in my 2016 Mazda 6 and never seen any improvement in economy.
_________________________
1984 Mercedes-Benz 300SD - 100k
1995 F150 XL 4.9 reg cab 5MT - 250k 5w30
2016 Mazda6 Touring 6MT - 56k 10w30

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#4450611 - 07/05/17 05:05 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
rollinpete Offline


Registered: 03/20/17
Posts: 461
Loc: West Ma.
Mine runs quiet on 89 octane...
87 octane and it starts pinging when I get on...
It calls for 87, strange that little bit makes a difference... shrug
So 89 is what it gets... smile
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Pete.
97 Ford Expl.Sport 4.0 ohv 4wd 5spddrive183k miles
Last Change;
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#4450623 - 07/05/17 05:31 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
itguy08 Offline


Registered: 09/15/11
Posts: 3227
Loc: Somewhere
I'll let my data speak for itself.... I own 2 twin turbo DI vehicles (Ecoboost 3.5) and both "do better on premium" but require only regular.

During the fall and winter the Taurus runs great on 87. During the spring/summer it runs OK but you can tell something is off. 89 or premium and it runs great. MPG is a little better at all times on premium but not enough to offset the $0.50 or so per gallon difference in cost. All MPG records are from new. It gets 87 in winter and 89 (or premium if I'm at Costco) in the summer. 117k on it and no issues whatsoever.

At all times the F150 gets regular. Towing or not towing, summer or winter. It doesn't seem to really mind the gas as much as the Taurus. Maybe I'd see better results in the West with steeper mountains but here in the East it's fine on all gas. I've tried premium and it does get better MPG towing or not towing but it's not enough to cover the additional cost. I've got 79k on it and bought it at 48k. All MPG records from day 1 of my ownership.

There may well be more power on premium on both vehicles but I'm not paying the dyno to find out. The F150 hauls the 9-10k camper great up and down the mountains and will keep the speed limit and above with no issue, even in the dead of summer.


Edited by itguy08 (07/05/17 05:32 PM)

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#4450629 - 07/05/17 05:38 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
Donald Offline


Registered: 03/21/04
Posts: 20469
Loc: Upstate NY
In some cases higher octane gas has more detergents that 87. But its the detergents that may help. Some cars recommend 92 octane but will run fine on 87, so if that's the case you will notice a difference with 92. Some cars require 92 and should also use 92.

Some engines may have carbon deposits that stay hot enough to ignite gasoline during the intake stroke. Premium may help there.

Many people buy premium and subjectively think the car runs better. So be it.
_________________________
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2015 Ford F250 w/Powerstroke
2016 Subaru Crosstrek CVT (wife's)


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#4450632 - 07/05/17 05:40 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
Shannow Online   content


Registered: 12/12/02
Posts: 39919
Loc: 'Stralia
decades ago, I had a 4Runner with the 3VZE...my first high comp (back then) Japanese motor with knock sensors. Engine had to work pretty hard to drag the 4Runner around at highways speeds.

Through diligent measurement on trips, the high octane always paid for itself in fuel savings on interstate trips...the engine could use the fuel...it's the only vehicle that I've ever had which had that marked difference. Around town could measure nothing.

The Caprice, L67, standard with 6lb boost was marked "premium recommended", but could run regular...would just detune spark and fuel poorer performance...however, fitting a 10 pound pulley, it no longer has the ability to run RUG.

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#4450646 - 07/05/17 06:06 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
ls1mike Offline


Registered: 06/14/08
Posts: 5121
Loc: In the Garage...
I can actually watch the computer pull back timing on the Caprice, Silverado and Trans Am. The Trans Am requires premium.
The Caprice and Silverado do not. If you don't think tuned to run on lower octane doesn't mean "Hey pull some timing out" Get yourself HP tuners and watch it. The truck is the worst. You can see it pull a ton of timing out with 87 Octane.
With premium you most likely can't tell the difference but your car knows.

I can certainly see it when towing and the MPGs on the truck.

The Caprice not so much but I can, with HP tuners at WOT see it pull timing back on 87 octane.

I have not messed the Malibu, however it only requires 87, but tells you that best performance is achieved with premium.
_________________________
Mike
00 Trans Am WS6 5.7 LS1
02 Silverado 2500HD 6.0
14 Caprice PPV 6.0
15 Malibu LTZ Turbo
12 Passport TT

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#4450664 - 07/05/17 06:34 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
901Memphis Offline


Registered: 08/14/10
Posts: 12893
Loc: Northern Kentucky
What about the detergent factor? If you want the cleanest for your port fuel injection you have to pay for shell premium which is loaded with goodies
_________________________
2012 Chevy Cruze LT 1.4T - 50k
2002 Buick Century 130k - Built 4T65e(Maxlife) - Edge 0w40 + Fram XG3980

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#4450708 - 07/05/17 07:23 PM Re: Higher octane than recommended a waste? [Re: PeterPolyol]
TurboFiat124 Offline


Registered: 04/29/12
Posts: 205
Loc: East Tennessee
I probably should have read some of the replies before asking this question.

I realize using higher octane gasoline in an older vehicle such as one with a normally aspirated 8:1 C/R engine and no engine management system is a waste of money but if a vehicle has an engine management system on it (no vacuum advance, external control model, etc.) where the engine uses a knock sensor to adjust the timing accordingly, is there any change using higher octane fuel would allow the engine management system to advance the timing further under cruise (until a ping is detected) to give more power or fuel economy? Or is the ignition timing set by the EPA to where it won't go above a certain degree? And you would have to buy one of those "power chips" to see any benefit?

I tried an experiment with my 2003 Subaru Baja one year. I had planned on replacing the tires before winter since this is my "snow vehicle" and decided to try something.

Before heading off to the beach, I filled up with 93 octane and inflated the tires to 45 PSI (the maximum cold pressure rating). I filled up about 300 miles from home and checked my mileage. Normally I'd get about 29 or 30 mpg. This time I got a whopping 33 mph.

I doubt that gaining 3-4 MPH would justify wearing out tires and the cost of higher octane fuel. My guess is over inflating the tires improved the fuel economy but the higher octane fuel did nothing. Also I may not have hit any traffic jams.





Edited by TurboFiat124 (07/05/17 07:25 PM)
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