Ive done some research and inquirys with master techs on the simple question - Whats the optimum fuel octane for your vehicle ?
. In simple terms - Mazda says 87 octane is ok - YET octane below that can potentially cause severe engine and emissions system damage !
WOW - That means that if you get depleated or cheap fuel thats 86 or below - look out !
At 87 you are effectively right on the edge of the absolute minimum needed to have these engines not get damage - !!
So we also know for a fact high COMPRESSION engines like MAZDAS SKYACTIVE 2.5 - both turbo and non produce more horsepower and torque with higher octane fuel 91+ instead of 87 ....which 87 as well often produces engine ping and knock
...a damaging occurence which the ECU MAY only remedy AFTER detection with electroniclly controlled timing advancment -
So why risk damage and sacrafice performance .....to save a few pennies ?

Mazda also recommends using 91+ octane when towing ? So wouldnt having a full 5 passengers and cargo be similar to towing ?
Max payload is about 850 pounds !
I would caution anyone with a skyactive engine to at LEAST USE 89 octane - and if you can go with 91+ - Once you stick with one octane your ECU will adapt and operate on memory unless a change is detected - but remember its difficult to know if 87 octane - (in which up to 10% can be enthanol ) is not 86 or lower - in which your ECU is not going to be capable of getting the engine to run properly !

 

My advice would be to always use a top tier gasoline… there is a lot of testing that is done before gasoline is shipped out of the refinery.

 

The top tier while more expensive has better formulas.

Chevron, Shell, Mobil, Union 76 are likely the top 4 in the US. Shell and Chevron based on their formula, history and empirically found information are the best. I prefer 76 (or *SoCal) because they still offer 100 octane fuel at a few locations for *track racing and other competition sports events...

 

That's a strange statement 95 or above and less than 98. Why not just say 95 or higher or are they concerned 98 and above may contain Ethanol?

 

Basic owners manuals are not always reviewed by Engineers before printing it generally editors looking for grammar flaws before final printing .So there is often some questionable info sometimes printed in the owners and even service information not just with Mazda.
For service manuals there are revisions or updates at time regarding some procedures and other service information .

They do not consider Gasoline formulas specifically if they may have Ethanol. If it were then you would see an asterisk with explanation information.

 

Try reading a genuine Hyundai workshop manual. Talk abt grammar errors and misplaced info..

 

Except for 2 Shell stations (and the airport), still 10% ethanol gasoline in my area.
And the Shell stations require a drive out of town.
Luckily one is only a 1/4 mile from the grocery store I shop at.

Our state passed a law in 2020 that no more ethanol blend was required to be sold here, but for some reason (profit) most gasoline suppliers still have not changed.

 

It is a less expensive formula. At least that what my friend's in Benicia CA refinery tell me.
My guess is that your state politicians look good changing a regulation that makes people feel better.
I do know via actually Dyno testing that running none oxygenated gas produces greater power levels closer to what the auto manufactures claims of engine power is. Thats another area that many don't read is what formulas auto manufactures use to determine what they are going claim the power output is of an engine.

 

In Georgia it's difficult to find non-ethanol gas in most areas. I live on a lake, and several stations around me offer 90 octane rec fuel with no ethanol. I use this in my Piaggio scooter and gas blower, as it won't gum up like ethanol gas does when it sits for a while. I have been using 87 almost exclusively in my '21 2.5T, and it runs great. I have used premium at times and feel no difference in engine performance, despite the claim it makes significantly more power with premium. If I were towing, I certainly would use premium, but that is a non-issue for me.

 

I don’t know the current situation, but previously the U.S. Government provided financial incentives for oil companies to produce biofuels… ethanol gasoline, biodiesel, etc…