Totally informal testing, but yes, I have run a number of tankfuls with 93 and 87. "Seat of my pants" tells me there is some definite responsiveness advantage with 93. It feels and sounds like its working harder with 87. Of course, it all could be mental on my part. In the end, any difference is negligible in daily driving, so I've decided that 87 will be my choice going forward.
Acceleration Times 227HP Vs 250Hp
- Thread starter Pitter
- Start date
Yeah I vote +1 for seat of the pants with premium, I am on my first full tank, not sure it makes much difference "technically" but I am interested to see if there is much difference as far as MPGs go.... I'll run out this tank then go to 87 a see. I can definately say you can feel it at highway speeds when you pull out to pass... instant smile....
You were rarely (if ever) evaluating true 87 or 93 octane, but rather a mixture of the two.
Say you switch from 87 to 93 octane, and typically pump 11 gallons every time you fill-up...
It would take SIX fill-ups before you tank contained nothing but 93 octane fuel.
All of the previous fill-ups would be an octane level somewhere between 87 and 93.
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- State of Jefferson
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- 2017 CX-5 GT AWD+
Once you've put that dirty old 87 in there, you'll never get back to pure hi test. It'll just keep getting more and more diluted, but not be totally gone.
But I agree, by 6 fill ups, you'll be close enough for government work.
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- 2019 CX-5 Signature
Dirty 87?
Also, every CX-5 turbo will be delivered to the customer with 87. Dealers will never put in anything higher.
Turborascal
Contributor
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- 2019 Mazda CX-5 Signature; 2019 Mazda MX-5 30 AE, RF, #150/3000
Not every turbo ... while I was awaiting paperwork, my sales person rode with me to a nearby station where the vehicle was filled with 93 octane on the dealer's dime. (drive2)
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- 2019 CX-5 Signature
It was driven to the gas station on 87, though. The dealer used 93 as an act of good faith, which is nice.
I live in an area that is represented by almost every auto manufacture. I have yet to see any dealer's BMW, Mercedes, Audi, etc get filled up with anything but 87.
After 6 fill-ups, the octane level would be 92.997
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- State of Jefferson
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- 2017 CX-5 GT AWD+
Sarcasm is often hard for some people to recognize.
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- State of Jefferson
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- 2017 CX-5 GT AWD+
I haven't done the calc, but I'm agreeing with you in principle. But while the limit approaches zero, it never quite gets there. Not that it matters in any practical sense.
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- State of Jefferson
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- 2017 CX-5 GT AWD+
No data, just thoughts.
1- Driver is less likely to hammer it as much with 87? Or to put it another way, a driver who doesn't care about that extra power will be a more sedate driver in general.
2- I have heard that lower octane fuel contain slightly, that is SLIGHTLY, less energy content due to the higher level of additives. True?
Several members are tracking the mileage diligently, so we should have more anecdotal data as time goes on, if they try both octanes.
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- 2021 CX-9 Sig
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- 2021 CX-5 GT
BS. I think the sales guy lied.
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- Central Virginia
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- 2019 CX-5 Reserve
I've run 3 tanks of 87 through my Reserve and 13 tanks of 93, and track my mileage every tank.
The computer average for those 16 tanks of gas is 0.5 MPG lower than my manual-calc average MPG, so the computer in my car for my environment is pretty accurate (actually surprising with all the hills & valleys here).
Based on my dataset, and going by the computer calc, I get 0.9 MPG higher with 93.
I ran a tank of 93 and then two tanks of 87, then two tanks of 93 and the 3rd (and last) tank of 87, so the 87 was actually a little higher octane. My last 10 tanks of gas have been 93. I have no intent of running anything but. The extra MPG narrows the cost difference to about $1.50/tank at today's price spread.
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- '22 X3 M40i
What kind of MPGs are you seeing the .9 spread between?
Excuse me, but I ran ~~10 tankfuls of 93 vs, ~~10 tankfuls of 87. I stand by my post. (drive)
You can't draw any meaningful conclusions from your 87 vs. 93 data.
The actual octane level across your first 7 fill-ups (where you switched between octane levels) was...
1 - 91.64, 2 - 87.83, 3 - 87.18, 4 - 91.34, 5 - 92.74, 6 - 87.86, 7 - 91.89
So you never got a true reading of 87 or 93 octane during those fill-ups. Any MPG difference you may have noted is not related to the octane level.
Also, for the last 9 fill-ups of 93 octane you posted in another thread, you had a variance of 4.5 MPG across those fill-ups.
This further underscores the point that you can't draw any conclusions from your tiny sample size of 3 87 octane fill-ups.
I'm curious how you calculate such a small price difference.
As noted above, your data doesn't support any MPG difference between the octane levels, so you should simply be looking at the straight price difference between 87 and 93.
In my area of the country, there is a ~$0.71 price difference between the two grades.
Your profile says you live in the rural part of central VA. In looking at a random gas station in Lynchburg, the price difference was $0.68.
So if you pump 11.5 gallons per fill-up (which is about your average), then premium would cost an extra $8 or more.
Are you saying you ran 10 consecutive tankfuls of 93, then switched to running 10 tankfuls of 87?
If so, then your last ~4 tankfuls of each are representative of true 93 and 87 octane.
You would have to disregard the first 6 tankfuls of each, as they were just a mixture of the two octane levels.
If you switched between 87 and 93 at all during those 20 tankfuls, then you were never truly evaluating 87 or 93 octane, as I stated.
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- Soon to be 2.5T CX-5
Yea, I did his math too and couldnt get it to add up at that low of a difference, even using the $.30 interval he posted between 87 and 93.
