Ok, we all know that Mazda says regular - 87 octane is fine and going to premium -91/93 octane gives ya more power. But with gas prices getting higher, has anyone changed from premium to regular? Last night I went to the gas station, gave the guy my card and he asked "regular" and instinctively I said, "no, premium please" and so he pumped away. But I took a look and there's a 50 cent difference between the two. Not an insignificant difference, though I'll probably still keep filling with premium. Then again, maybe I have it all wrong.....

 

Premium around here, Wisconsin, can be 73-80¢ over regular. But it is non-alcohol.
I don't drive with a lead foot, but I have filled up with regular a couple of times. I can feel the difference, but
it's not a great difference for my driving style. Not it heavy acceleration.

My 2¢

 

It just depends on what you want. Neither grade is going to harm the engine as it is designed to worth with both 87 and 93. I haven't used regular yet, but I suspect the car is plenty strong with 87 as it still produces 310ft/lbs.

 

Understood about not harming the engine and loss of some power/torque but this is my question - But with gas prices getting higher, has anyone changed from premium to regular?

 

Do you have a turbo engine or a naturally aspirated engine?

 

Turbo.

 

My experience with Corvette engines that had a factory 93 octane requirement was that there are built in knock sensors in the engine that detect detonation in the engine and automatically retard the timing to limit any damage it would potentially cause. Contrary to lot of information out there, higher octane gasoline does not give you "more power". The higher octane fuel is simply formulated to reduce the issue of detonation in higher compression ratio engines or those with artificial boost such as a turbo engine. Higher octane does not "boost power", it just keeps your engine control computer from retarding the timing due to detonation detection. In virtually all computer managed engines, the system will not let you "hurt" the engine by using lower octant fuel.

 

I have changed from 93 to 89 octane, to save money. Indistinguishable performance or mileage for my normal suburban driving. If I get out into the open and floor it until I reach 80mph or so, I miss the 93 octane.

Frank

 

Gasoline run engine only:
To preference my experience regarding DYNO TESTING and Performance levels of engines:
I have done several Dyno runs that I don't publish with my 2.5 Skyactiv normally aspirated MAZDA 3 . But really to save debates from some that have yet to do this, or anyone that has not watched their ECU information output when you use different octanes please go to your local shop and get a few runs of DYNO Chassis experience before responding in debate so we at least can have a little of the same basic reference to talk about. I might also include here that I have own 3, yes 3 Dyno's, an Engine Dyno, portable Chassis DYNO and a fixed mounted shop Chassis Dyno. And until resent changes in California Laws I ran Chassis Dynos for another shop and for Car events with a portable Dyno. So ya hundreds of personally performed Dyno runs. I also pride myself on accurate programming input set up of the DYNO for more real world accuracy of results and repeating the Delta's for a return DYNO run on different days.

The ECU will compensate for use of lower octane levels(to a point) , how it does this is by adjusting
operating perimeters with fueling and timing to name the 2 most common cells from input of various sensors to the ECU. This WILL and DOES lower the torque and Horsepower output. Please remember that when you are talking about power the rating and Mazda's currently are not participating in the automotive industries CERTIFIDE power levels for legally publishing "TRUE" engine output levels. You may also understand that most published power rating are at or close to the maximum safe operating limits of the engine RPM.
And no the MYTH about deducting a percentage of a exact number is so inaccurate I am surprised it is still mentioned. Even between a manual and automatic transmission. Especially if you understand that Mazda's automatic transmission are totally different then the decades old TECHNOLOGY of how automatic transmission work.

Regarding MAZDA TURBO CHARGED engines unless they specify to use ONLY a octane rating your TURBO CHARGER is safe as I already described how and why above.

The use of a specific OCTANE in most normal operation for MPG will not change enough that it matters in unless you live in a mountain City or town that the elevation changes and the throttle must be used to maintain your choice of speed. Or if you load your MAZDA weigh capacity or tow with it and naturally if you performance or drive spiritedly. Then common sense use a higher octane fuel. The knock sensor ( on all vehicles only report a limited amount of information) can not adjust for all load variables and actually is still very limited and ECU can only compensate on small levels of adjustment under loads using lower octane levels without finally engine KNOCK. The ECU can in some model be calibrated differently but this requires not only a trained level of experience in PERFOMANCE ECU/EFI Calibration but a devise to access the full access of the auto manufactures ECU and all the PIDS or cells to make adjustments. I have yet to see anyone offer it, FULL ACCESS for MAZDA ECU with automatics that include the needed TCM calibration changes required when changing some ECU calibrations!

 

I might add at this point that if you all want to protect your engine and gain some power improvements especially with a Turbocharged or Supercharged engine is to invest in a water/meth system. These are not necessarily restricted to only one use vehicle and can be removed and installed on several types of gasoline engines. So it is a good investment on this and your next MAZDA.