Octane?

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CX5 GT-R
Thanks for finding this AAA Premium Fuel Research report. I guess this conclusion from the report should summarize it all:



My biggest question is why the "real-world" horsepower is only about 80% of the rated horsepower on paper? The 3 test-runs for maximum horsepower on Mazda3 Grand Touring 2.0L I-4 which has horsepower rating at 155 @ 6000 rpm are 126.28/126.79/126.54 hp with 87-octane regular fuel and 129.78/129.25/129.52 hp with 93-octane premium fuel. This happens on all 3 test vehicles, a Tundra 5.7L V-8、a Charger SXT 3.6L V-6、and a Mazda3 Grand Touring 2.0L I-4. Why the discrepancy is so huge? (uhm)

So mazdadude, you won't get 188 hp with your 91-octane premium in reality, you can only get 152 hp at most from your 2.5L! (boom08)

126bhp? Really? That's about what an automatic 2002 Infiniti G20 I4 2.0L (I had one) dynoed. Mazda needs to step up. It's not 2002 anymore!
 
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13' CX-5 and 16' Mazda6 both Touring w/Tech/Bose
The safe buffer is already present. It's called your ECU.

This is craziness. Just buy 87 unless you are competing with someone in a dyno-test war.

A good 1 1/2 years later........

Okay I've been using 89 octane for well over a year. So I needed gas bad but nearest station only had 87 octane. Shell. Filled up. Man 87 octane felt zippier. For us spec CX-5's MAzda3's and Mazda6's....NA models....just use 87. Don't go against the grain on the ECU tuning.

Miata's and turbo models use 90+
 
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2018 3 Sport GT MANUAL
I think it's likely more important long term to get good quality gas from a reputable supplier (injectors, deposits etc).

Up here in Canada I find PetroCan gas is awful personally. Chevron and Esso are good, Shell 'ok'. Otherwise, just put the gas octane in your manual calls for.
 
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2017 CX5 AWD Touring
The AAA report quoted earlier in this thread showed the Mazda SkyActiv high-compression engine gained 20HP at the crank with the high octane.

I only use 91+ in the summer and when towing. When I ran 87 octane in the summer, towing a trailer, climbing a grade, the engine would pull some wicked timing and the CX5 would not fair well. Once I ran the 91+ mix, it didn't pull the timing like it did with the 87 octane.
 
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CX5 GT-R
The AAA report quoted earlier in this thread showed the Mazda SkyActiv high-compression engine gained 20HP at the crank with the high octane.

I only use 91+ in the summer and when towing. When I ran 87 octane in the summer, towing a trailer, climbing a grade, the engine would pull some wicked timing and the CX5 would not fair well. Once I ran the 91+ mix, it didn't pull the timing like it did with the 87 octane.

On a hot day, totally possible. I know LS1 cars heat-soaked bad at the track, for a drag-racing datapoint. That said, why bother? It's for economy, not for speed, so get your economy, unless you're taking it to Import Tuner Night on a hot, muggy Saturday night.
 
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2017 CX5 AWD Touring
On a hot day, totally possible. I know LS1 cars heat-soaked bad at the track, for a drag-racing datapoint. That said, why bother? It's for economy, not for speed, so get your economy, unless you're taking it to Import Tuner Night on a hot, muggy Saturday night.

If I am pulling a trailer, up a grade, in the summer, I would rather pay the extra few bucks for 91+ octane than deal with timing being pulled and the vehicle falling flat on its face.

10 gallons of 91+ is only $3.00 more vs 87 octane. Worth it for me when the above is at play.
 
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CX5 GT-R
If I am pulling a trailer, up a grade, in the summer, I would rather pay the extra few bucks for 91+ octane than deal with timing being pulled and the vehicle falling flat on its face.

10 gallons of 91+ is only $3.00 more vs 87 octane. Worth it for me when the above is at play.

Sure, I get that, but I mean as a daily matter of course.
 
Does high octane really affects SkyActiv engines?

AFAIK the difference between 87 and 91 octane is that the 91 has a higher tolerance for compression ignition. Other than that, I don't know of any.
 

yrwei52

2016 Mazda CX-5 GT AWD w/Tech Pkg
Contributor
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Plano, Texas, USA
Does high octane really affects SkyActiv engines?

AFAIK the difference between 87 and 91 octane is that the 91 has a higher tolerance for compression ignition. Other than that, I don't know of any.
Depending on your driving situation. In harsh condition such as Lbear mentioned above, higher octane gas definitely will help high-compression SkyActiv-G engines performing better! TheMAN said it the best:

very simple... just like any other engine/car out there, the ECU's strategy to avoid/prevent/stop detonation under the right conditions (hot weather, high engine load), is to run the engine richer (increase injector duty cycle, reduce ignition timing)... since the SkyActiv is known to run in full closed loop ECU operation (knock sensor is utilized at all times), running high octane gas WILL allow the fuel mixture to be leaner, thus excess unburned fuel will not get "washed down" past the piston rings into the oil pan

oil analysis reports can be found on other forums that proves this
 
Depending on your driving situation. In harsh condition such as Lbear mentioned above, higher octane gas definitely will help high-compression SkyActiv-G engines performing better! TheMAN said it the best:
Thanks. Based on his post, he said for SkyActiv engines, it will run leaner. Meaning less fuel.
 
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CX5 GT-R
I didn't realize you had the Sentra gt..sorry

Aside from maintenance issues, it was actually a pretty neat little vehicle. I used it as a daily when my fun car was a C6 Z06. It got 31mpg on long road-trips doing 80mph, and it had more technology and features than my 2015 CX5 Touring.
 
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2015 CX-5 GT AWD liquid silver
Last year, when we were on summer vacation, I was driving from eastern Tennessee through western N Carolina and I filled up on premium gas because I remembered this thread and I knew that we would be heading into the Appalachian mountains. I had the Mazda loaded up (Wifey, beach chairs, tent, cooler, luggage, ETC). It seemed to me that the car drove well through the mountains. I think that the premium helps and will run premium again when I drive through that area again. Could this be the placebo effect? Perhaps, but it seemed real enough to me that I will pay the extra for high test gas next time I'm there.
 
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13' CX-5 and 16' Mazda6 both Touring w/Tech/Bose
Last year, when we were on summer vacation, I was driving from eastern Tennessee through western N Carolina and I filled up on premium gas because I remembered this thread and I knew that we would be heading into the Appalachian mountains. I had the Mazda loaded up (Wifey, beach chairs, tent, cooler, luggage, ETC). It seemed to me that the car drove well through the mountains. I think that the premium helps and will run premium again when I drive through that area again. Could this be the placebo effect? Perhaps, but it seemed real enough to me that I will pay the extra for high test gas next time I'm there.

Like I said I've been running 89 for a whole 1 1/2 years. Went to 87 and felt a noticeable zippy difference. I'll try another tank of 87 from a different station this time.

If it is the placebo affect then hey I like it :)
 
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2013 CX-5 6MT
The AAA report quoted earlier in this thread showed the Mazda SkyActiv high-compression engine gained 20HP at the crank with the high octane.

I only use 91+ in the summer and when towing. When I ran 87 octane in the summer, towing a trailer, climbing a grade, the engine would pull some wicked timing and the CX5 would not fair well. Once I ran the 91+ mix, it didn't pull the timing like it did with the 87 octane.

you might want to read that study again. The gain was 2HP! not 20!