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Discussion Starter · #1 · (Edited)
Didn't see this posted on here yet, so here it is. The Mazda cars they tested were a 2.0L 2015 Miata and a 2016 Mazda3 2.0L . BOTH showed improvements (however small) in HP, Torque, and fuel economy.


Will you feel the difference? Probably not.
Will you save a ton on fuel costs. Not in the least.
Is it worth it? For the price of a Starbucks coffee, I'll gladly spend extra $$ on Premium over Regular fuel at every fill-up, even if I wasn't tuned. My last 3 cars used Premium so I'm used to the higher price. And I hate coffee anyway.

- EDIT: Meant to post this in 2014-2018 Forum. Mods please move.
 

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Not for nothing but 2 hp is well within the margin of error on a dyno.
To make any real difference, the ECU has to have maps for the fuel type used. Non turbo Mazda engines are mapped for 87 octane.
The following quotes say all you need to know-

4.2 Findings: Maximum Horsepower
The vehicles tested did not produce more horsepower when using Premium gasoline. While some differences were recorded when comparing Regular to Premium fuels, they are very small, and are within the expected differences in run-to-run variation for maximum horsepower testing. The data collected does not support any conclusion that Premium fuel allows a vehicle designed for Regular to produce more maximum horsepower.

5.2 Findings
Fuel economy is not improved overall when using Premium in a vehicle certified for Regular octane gasoline. From a fuel cost perspective, the test results do not support spending the extra cost per gallon to put Premium in the tank of a vehicle designed for Regular gasoline.

6.2 Findings
The amount of variation found in testing is normal for emissions testing, as there will always be some variability. Referencing the chart below, no consistent differences were recorded for the different emissions components across the three test vehicles and the three driving cycles. Carefully measured tailpipe emissions are not uniformly less on Premium than on Regular fuel.

7 Summary Recommendations
The automobile is often a person’s second most expensive life purchase. After depreciation, fuel costs are likely to be among the highest spending category for annual cost to drive. With the trend toward vehicles costing more and lasting longer, it makes more sense than ever to take care of your car. Based upon AAA’s testing, motorists are not treating their vehicle in any meaningful way by using Premium when the vehicle is designed to run on Regular fuel.
 

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These premium fuel for the Mazda3 threads appear every so often across numerous Mazda forums and subreddits. I'm not sure what the obsession is to self-justify the desire to use premium fuel. Is it a belief that 87 is inferior? Bad quality? Bad for the engine? What is it? I'd really love to know.
 

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The UK doesn't have 87 octane fuel. The lowest octane we have is 95, I run premium 99 octane fuel in my mazda 3. I'm assuming the ecu tuning is different on UK/Euro models than what it is on US versions.
 

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Octane ratings are done differently in Europe. Your 95 is 91 in the US.
Using 99 (93 in the US) does nothing but empty your wallet faster....
unless of course the engine can make use of it.....

 

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Discussion Starter · #7 ·
These premium fuel for the Mazda3 threads appear every so often across numerous Mazda forums and subreddits. I'm not sure what the obsession is to self-justify the desire to use premium fuel. Is it a belief that 87 is inferior? Bad quality? Bad for the engine? What is it? I'd really love to know.
I've read all of those threads on this forum, and none of them ever referenced any in-depth studies. It's good to see some actual results from real tests for once, instead of people just throwing opinions every which way.
Also, it's already conceded.. Even though there's a very slight improvement, you WON'T feel a difference, and you WON'T save cost on fuel.. So what's the obsession again? I guess it's the same obsession people have with buying bigger rims or modding their cars, or waxing their cars... (see below).

Not for nothing but 2 hp is well within the margin of error on a dyno.

4.2 Findings: Maximum Horsepower
The vehicles tested did not produce more horsepower when using Premium gasoline.

7 Summary Recommendations
Based upon AAA’s testing, motorists are not treating their vehicle in any meaningful way by....
There'll always be variances, but it's at least good to see that in ALL the trials & tests, Mazda GAINED power & fuel economy from Premium fuel, however minute that improvement was. Yes there is a margin of error, BUT.. Unlike the other cars, the margin of error never produced a NEGATIVE gain for Mazda. Is that conclusive? Definitely not, but it's encouraging to see nonetheless.

It's easy to see why they keep saying "The data collected does not support [this] conclusion..". Of course a 1% gain in fuel economy (per the test results) does NOT justify the extra cost of premium for 'most' drivers, especially if your goal is to save money... Which I 100% agree with, that you're NOT going to save money from buying Premium.

However, those of us who want the BEST for our cars are not always looking to save money ;)
1% better in a multiple test results is still a 'possible' 1% improvement in real world driving. At least now everyone has some actual facts to go on, and can make their own decision on whether they want to spend extra $$ on something that's "possibly" 1% better.

Mazda has turned the engine in the 3 for 87.. just throwing $$$ away running premium unless your running at tune setup for premium!
We all throw away $$$ on most things we do.. Modding cars, caffeine drinks, etc.. One could make an argument that buying Premium for your Mazda is a better way to "waste" your $$$ than buying coffee every morning 😝

So why buy Premium? I mean...Why buy 19" rims, or ridiculous aero kits? Why spend time and $$$ to clean your car? Why even buy a new Mazda and possibly blow the engine tuning it, when you work remotely from home and already have a reliable Honda in the garage? It's all just $$$ down the drain anyway lol.

This is why.....
Regular Coffee at Starbucks: $1.85
Mods for your car: $1K+
Feeling good about what you do to your car: PRICELESS :)

-
 

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Yes on a standard engine the differences would be negligable. But would it make a difference on mazdas skyactiv x engine? The high compression 2.0 litre supercharged engine, (Not sure if you guys in the US have this engine.)
With a much higher than average compression ratio of 16.3:1 it could, theoretically, make use of high octane fuels.
 

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Tuning is the key. If the ECU is mapped for a certain octane (87 in N. America), use that octane.

You will get the best performance and the best mpg possible at a lower overall cost.

If you want to use a different octane fuel, get a tune specified for it. That way you can reap the benefits of the added octane.

I'm tuned for 91 octane and get more HP, more torque and better mpg than I did on my stock tune. They even have tunes for people wanting better mpg only. Lower avg RPMs.. more torque.
CK
 
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Discussion Starter · #11 · (Edited)
I've found this from a FB Mazda 3 group I'm in and it seems to suggest it makes a non-negligible difference: ECU Self Learning
"Car had less then a gallon of regular when I picked it up. Car had 12 miles on it and generally takes 50 or so miles to set fuel and timing trims.
Once I picked it up I put 91 octane premium in it. Car has never seen anything less since."


Not sure I see the relevance of Premium vs Regular being tested there.
The car only ran on 91 octane the whole time..


Tuning is the key. If the ECU is mapped for a certain octane (87 in N. America), use that octane.

You will get the best performance and the best mpg possible at a lower overall cost.
I assume most know this already about tuning. And again, it's been established that using Premium is NOT for lowering fuel costs.

The question being asked is simply: Is Premium better than Regular fuel for Mazda engines (specifically Skyactiv-G in this scenario)?

The only in-depth test results we have seem to suggest that there is an improvement with Premium, however small it may be. The statement of whether it's "worth" it to use Premium in your Mazda is and always has been an opinion, unless someone can point to another test showing otherwise.

I'm simply looking at the facts of the test results.


Not sure why people are so hell-bent on dismissing this "possible" benefit of Premium fuel. Especially with evidence of a REAL in-depth test results right in front of them. You'd think on a Mazda-lover forum people would be excited to see these results.

No one said this will turn your car into a rocket, or save you big at the gas pump. There's simply a minor "improvement" shown in the results using Premium, after multiple tests... on 2 different Mazdas no less.
 

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Not sure why people are so hell-bent on dismissing this "possible" benefit of Premium fuel. Especially with evidence of a REAL in-depth test results right in front of them. You'd think on a Mazda-lover forum people would be excited to see these results.
The only "excitement" is that the test proves what most of us already knew. Using premium fuel with a Mazda 3 tuned to run on regular is totally pointless. A 1% change in power is meaningless. These power plants are mass produced and the variation in output between individual engines is almost certainly greater than +/- 1%. There is no way anyone could detect such small changes from the driving characteristics of the car.

A more "exciting" test would be to take 20 identical Mazda 3s, all with a few thousand miles on the clock, run them on the same dynamometer and see what variation in power they give.
 

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Discussion Starter · #13 · (Edited)
The only "excitement" is that the test proves what most of us already knew. Using premium fuel with a Mazda 3 tuned to run on regular is totally pointless. A 1% change in power is meaningless. These power plants are mass produced and the variation in output between individual engines is almost certainly greater than +/- 1%. There is no way anyone could detect such small changes from the driving characteristics of the car.
Again, it's been CLEARLY established that you CAN'T feel the difference. No one is disputing that.

And the results seem to contradict those who "claim" to lose power or fuel economy, or didn't "gain anything" from Premium... because they "felt" it? lol.. Seems obvious those people did not know this already.

And actually, there's at 2-3% increase in power. The 1% is referring to increase in fuel economy. Yea, I know... minor. And you still won't feel it in the real world. But let's not get the facts mixed up by posting "pointless" opinions.

FACTS in this Test:
2-3% power increase, for BOTH Mazda cars
1% increase in fuel economy, for BOTH Mazda cars.
Neither resulted in a 'negative' gain.. not once.
No, it's not 100% conclusive.
No, you WON'T feel this gain in the real world.

Whether it's a "meaningful" gain is irrelevant. This test simply shows that there is a gain.
Again, not sure why all the bitterness about THIS independent test result that no one has apparently read lol. Everyone needs to leave their pre-conceived notions about Premium fuel at the door.. unless you have another in-depth test to show otherwise.

Some wax & polish brands protect your car paint 1-3% better than other brands. Some oil filters filter out 1-3% more debris than others. Would you still pay MORE for that premium brand? Is that 1-3% "meaningless"? Not for everyone ;)
And you would never be able to feel those results in the real world either.
 

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I use ethanol-free premium in my '17 Mazda6 because I believe it reduces the tendency of the engine to add fuel to reduce knock... a behaviour in Honda 1.5T engines that dilutes the motor oil with fuel. Please note that I am NOT saying that that Skyactiv-G engines have a prb with motor oil fuel dilution. Just saying that the knock detector will detect knock at a later time when burning premium.

I also note that intake valve closure delay and ignition timing cut-back are other parameters that are used by the PCM to react to the onset of knock (in addition to fuel enrichment).
 

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Discussion Starter · #15 ·
I use ethanol-free premium in my '17 Mazda6 because I believe it reduces the tendency of the engine to add fuel to reduce knock... a behaviour in Honda 1.5T engines that dilutes the motor oil with fuel. Please note that I am NOT saying that that Skyactiv-G engines have a prb with motor oil fuel dilution. Just saying that the knock detector will detect knock at a later time when burning premium.

I also note that intake valve closure delay and ignition timing cut-back are other parameters that are used by the PCM to react to the onset of knock (in addition to fuel enrichment).
That's something I've always wanted to see tested too. I've always suspected that might be the case, but didn't want to speculate..
 

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argh... so stupid they did the tests and in all cases they're using ethanol crap... biggest diff is achieved by avoiding ethanol but they didn't show that unless I missed it... please tell me it's there :(

"AAAresearchers used EPA Tier 3 certification test fuel with 10% ethanol content in both regular87 octaneand premium93 octane((R+M)/2 method) varieties. "
 

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Discussion Starter · #17 ·
Since AAA is headquartered in the U.S., it'd make sense to do the tests here as well.. And 10% ethanol fuel is the most widely available.. which ends up being the most frequently used fuel by drivers. They would have to do the tests using what most people are filling their cars with, as these tests seem directed at the mainstream consumer.
 

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Assuming a 2.5 engine with 184 hp, thats 5.5 hp at the crank, maybe 3 at the wheels....sorry, no difference...certainly not enough to justify the cost of premium fuel.
 

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Assuming a 2.5 engine with 184 hp, thats 5.5 hp at the crank, maybe 3 at the wheels....sorry, no difference...certainly not enough to justify the cost of premium fuel.
I would like to chip in a minute, I own a 2019 AWD Mazda 3 hatch, automatic, and on 87 gas, I get 26 mpg on the freway, and on 91 gas, I get 32 mpg, and thats been a constant, same route, same time of night, with AC on, same speeds, there is a mpg difference, and i have been doing this for 6 months now, and the engine idles smoother too, power gain, hard to say, its gutless no mater what.
 
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