This is my first car with a high compression gasoline engine (I’ve owned 3 diesels). Are there any positives about using 87 or 91 fuel.

 

Yes!

However stay off the internet and most forums to get the empirical information. Most is DIY and not really accurate as most do not understand the ECU programing and how a variable camshaft with a Skyactiv engine works.
It also is dependent on which fuel companies you choose.
Top fuel station I highly recommend that you use USA based. These 2 are my go to gas and seldom unless in a situation that necessitates using another brand always use.
My preference for the Mazda Skyactiv engines is Chevron.
Chevron
Shell


These are a few testing's equipment that I came to my conclusion years ago using a Skyactiv Engine..
Naturally to be clear on this thread we are talking about a Mazda Skyactiv gasoline fueled engine.
See: Ultra Gauge
See: Autometer D-Pic
See: versa Tuner
See: how to use an automotive oscilloscope
See: how you measure specific gravity of fuel
See how to Data Log a ECU targeted run
See: Dyno Jet and Super Flow Chassis Dyno

To name a few benefits

Better overall MPG on all types or operating conditions.
More consistent power levels(torque)
Better combustion temperature control
Easier on the engine over all less knock control needed, no inconsistent timing and fueling changes
Cooler average CAT temperatures
The additives in the 2 mentioned are some of the best in the industry to help keep the fuel system clean.


The number one argument against using the higher octane fuels is cost. This is in the long term ridicules based on service that balances issues and problems less when owners use top tier fuel and higher octane gas. Better independent service shops will state this as well.

 

Thank you for your informative reply. No Chevron here in the NE but Shell is common.

 

Your best bet is to get gas from top tier gas stations (i.e. Shell, Mobil, Costco, etc). On the Naturally Aspirated engines you're fine with 87, and use 91+ when towing or moving heavy loads (per the manual). On the Turbo Engines, you want to use 91/93 for the most performance possible. It is safe to use 87 octane but the car will de-tune itself 26-30 horsepower and 10 foot pounds of torque according to Mazda to compensate for the lower octane gas.

 

Not exactly sure where u got that info Alexmed, it is not really accurate.
Costco uses to many different suppliers and therefore unpredictable.
Your thoughts about a boosted engine are not really inline with how it works with a Skyactiv Mazda engine.
You do realize that most average drivers of a Turbocharger engine are not boosting or boosting very little overall? But when they do the fuel quality and octane matter . Also keep in mind we are also talking about a Mazda specific Skyactiv engine engine . Look at my signature no Turbocharger.

Not sure how you can state to anyone that the use of 87 octane fuel will be ok? You need more Q&A from the op to make a claim like that and then it would only be a guess on your part.

The ECU do not “deftune” not sure where you got that phrase? All ECUs in the Mazda Skyactiv gasoline fueled engines are programmed to control engine and transmissions operation based on what the sensor inputs are.

Lastly Mazda power specifications are not certified so unless you do a Dyno test you are buying into a great ad to sell an automobile. Unless the auto manufacturer participates by way of a certification an auto manufacturer can state any power numbers they want. With the certification you can be sure that is the correct power rating specified.


I hope that you are not taking you own advise …. Maybe invest in an Ultra Gauge and use it for 6 months and learn some things about what goes on with your engine?

 

deciding how to take care of the car depends on how long you think you are going to own it. If your leasing it for 3 years....use whatever gas makes it run. If you think you can feel the extra HP with the turbo using 93 octane, go for it. ... On my 16 year old Miata. 93 octane Shell or 76 goes in it. On this my second cx-5...where ever my wife wants to stop for gas. Most of the stations in northern NJ are all top tier. Here costco sources their fuel from Mobil.

 

there are 68 top tier gas brands in the US...take your pick...
https://www.toptiergas.com/gasoline-brands/

https://www.consumerreports.org/cars/fuel-economy-efficiency/top-tier-gasoline-worth-the-extra-price-a7682471234/

https://newsroom.aaa.com/2016/07/aaa-not-gasoline-created-equal/

 

Look dude top tier advertised in no means the better-quality gas. Do your homework on real world testing and stop being the SUPER internet surfer finding partial information on the internet. Most is of those you posted are geared to you buying laterally their products. Follow where that information was generated from and you will have a partial answer to this. Then go directly to the companies that supply the gasoline and actually learn how it all works from the oil barrel to your gas tank?

Please tell me one thing...
when you compared the gas from various suppliers you posted top tier gasolines drove about 5k miles and scoped your combustion chambers what did you learn?
And maybe re-read post #2 & 5 again?

 

While this is your thoughts and it may work for your household budget or convenience it may catch up to you at some point with service issues? . As for Costco using Mobile, have a look next time at the Tanker that delivers it. Sorry to disillusion you but it is not that same Mobile gas from there retail advertised station as the one that you get from Costco. Call Mobil and ask them directly better yet email them your question and post the response on this thread!

And maybe re-read post #2 & 5 again?




I never should have used the word s TOP FUEL STATION in my first response here, so many just don't really totally understand the term and how it is used to sell products. I should and will in the future use BETTER FUELS

 

sorry bro, don't have time to do that level of research as i'm not retired...i, like most on this forum, just post and wait for you to tell us we are all wrong and what is correct according to the car gods...so please provide us with a list of what brands are considered "top tier" or "better fuels" in your eyes so we can get our enlightenment for the day cause not everyone has a chevron or a shell near them