Well, Mazda recommends 91 octane for maximum performance use, such as hauling heavy loads, towing, and climbing mountain roads. The higher octane reduces incidence of preignition damage while improving performance - 250 hp instead of 227 hp.

 

Exactly. If the engine produces the best hp/tq figures with 91+ octane, this would be the recommended fuel, right?

 

I did a quick search in the owner's manual (PDF file) and I don't see that Mazda recommends 91 octane, EXCEPT when towing.
I have attached screenshots from the Owner's Manual. Just to be clear, this is a US CX-5 and it's Owner's Manual.

 

if your a speed junkie.....you get 23 extra HP with higher octane.....and thats basically it...the computer adjusts timing to the changes...in the old days...we used to have to get out a timing light and rotate the distributor....

 

I am not sure if your are supporting my responses or what????

But I can see that your comment about the distributor leads me to think....mmmmm.
The reason that MOSRT auto manufactures "REQUIRE" higher octane fuel is for the obvious reasons. But not to or to suggest that the use of higher octane only supports power is inaccurate. Higher octane levels with the average driver will help support a more consistent and, in some cases, higher MPG. And for the experience using the instant MPG monitor can improve MPG using higher octane fuels.

For the DISTRIBUTOR comment. First it was "KOOL"! but then you forgot to mention changing the Dwell, the counterweights, thee counterweight springs and possibly plugging the vacuum advance. Turning the distributor on an unmodified Distributor more cases caused more problems than cures without doing it correctly.

 

yes....those were the days...but i assume the whichever octane you choose, the computer advances or retards timing to avoid pinging, hence a small boost in dyno numbers?

 

Its a common sense assumption that this is done regarding the ECU/ECM/PCM on vehicles, so sort of but not always and not really so much with the MAZDA. Maybe read my previous response. Specifically, the Skyactiv ECU. I have been developing power parts for the 2.5 and have monitored what the ECU does. I did about a year ago run one complete tank of 87 octane Chevron and compared the results and data logging on which was close to the exact same miles and travel route. I can tell you everything was less, power and MPG. While I did Not DYNO the 87 because (WHY), (LOL) I have run several DYNO runs setting up and running the same DELTA each time from the base line completely stock MAZDA 2,5 to each addition I made on the engine or something that may affect the engine output?

 

just to go back to your original comment on MPG's i can say for sure., my 09 lexus gx470...."recommends" 91 octane...and when I tracked my gas usage i clearly squeezed a few extra miles out of a gallon of gas when using the higher octane and thats not saying much...going from 14 to 17 mpg...at least it offsets the increase in the price of that gas.

 

I am always chuckling when someone spends the amount on a new vehicle and then wants to stretch all the service schedules like oil, filters, spark plugs, etc., and then NOT to use and spend a little extra for a fuel that will achieve the best overall performance from the engine????? REALLY you all are just funny! Maybe it just to talk on a forum but I can tell you in the shop back lot we are now 2 weeks catching up on customers cars for service needs. And some of them are complaints about power and MPG. They all have that one common fact, use of low octane fuel and not changing the sparkplug's (usually the average is 40Kmiles) until a DTC P300-P308 is found in the OBDII.

ASE

 

DITTO. Unless you have the Turbo, why would you want to use anything OTHER THAN 87 Octane gas? Do you have money that you regularly burn to start your grill in the evening? Please send the extra money to my personal charity if you have no use for it. Or send it in to help pay down the $29 Trillion U.S. debt outstanding.

"Cheaping Out"..... You kill me.

Best Regards, RMV