Question for turbo owners: what octane do you use?

What octane do you put in your CX-5 turbo?

  • 87

    Votes: 17 38.6%

  • 89

    Votes: 2 4.5%

  • 91

    Votes: 8 18.2%

  • 93

    Votes: 17 38.6%
  • Total voters
    44
B

BirchBarlow

Member
:
2017 Honda CR-V AWD
Obviously the gasoline recommendation for this engine is a bit unusual. Most premium vehicles like Acuras, BMWs, Audis, etc. stipulate 91 as the minimum. Mazda, of course allows for 87 but recommends 93 for optimal performance, which begs a couple questions for those who have first hand experience. Is there a noticeable difference in performance and/or gas mileage between 87 and 93? Does the engine run better on 93? If there is a perceptible difference between 87 and 93, what about 89? Is still worth purchasing the turbo if your intention is to run 87?
 
87 gives plenty of power for me so thats what I use, its fine. This car already gets not very good gas mileage so using 93 will increase the expense even more. But if you feel a need to drag race your CX-5 and get to 60 a half second earlier, go nuts with 93. Personally I dont see the point.
 
Maybe I missed it, but where do you see they "recommend" 93?

We have about 30 miles on our CX-5 Signature, so obviously still on dealer fill 87. I will fill it with Premium as soon as we run it down. That said, it feels very peppy on the 87. I would have no problem using that grade for normal driving. According to C&D you can get 0-60 times in the low 6 second range on Premium. I'm guessing a 1/2 sec change on Regular, but have no proof. I really like the fact that they show spec's for both grades. That means there is actually a benefit in using it. Unlike the CR-V, which you're familiar with.

Are you jumping ship, too? :)
 
Right now at my local station, 93 octane gas is $2.29 per gallon. That makes it a no brainer. We will see what I do if the price goes up to $3.29 per gallon.
 
kone said:
For +25hp it*ll be 93 for me. At least as long as gas prices stay low.
Click to expand...

It's my understanding that the +27 HP is ONLY realized ABOVE 4K RPM so I'm not sure I see the point of 93 vs 87 given the 310 lbs of torque for either.
 
I have my wife using too tier premium for now.

As far as power goes yest there's only an additional 27 HP with 93 octane but that HP increase doesnt tell the whole story. With 87 octane the power and torque falls on it's face over 4000 RPM. With 93 octane the torque curve is flatter rather than dropping off quickly and feels more powerful over 4000 RPM. This means you will rev higher and when shifting to a higher gear you will still be in the prime area of the power curve. So peak torque doesn't increase with 93 octane but the torque curve is flatter to higher RPM'S

If you never enthusiastically drive the 2.5L turbo engine then 87 ictane will do... but then again the NA engine might have been enough in the first place.
 
SignatureCX5 said:
I have my wife using too tier premium for now.

As far as power goes yest there's only an additional 27 HP with 93 octane but that HP increase doesnt tell the whole story. With 87 octane the power and torque falls on it's face over 4000 RPM. With 93 octane the torque curve is flatter rather than dropping off quickly and feels more powerful over 4000 RPM. This means you will rev higher and when shifting to a higher gear you will still be in the prime area of the power curve. So peak torque doesn't increase with 93 octane but the torque curve is flatter to higher RPM'S

If you never enthusiastically drive the 2.5L turbo engine then 87 ictane will do... but then again the NA engine might have been enough in the first place.
Click to expand...

Yeah, the curve are identical for 93 and 87 octane until 4000 RPM, where with 93 octane keeps rising and the 87 octane starts flattening out and starts dropping at 5000 rpm. The torque with 87 drops to ~225 lbs while with 93 it still looks to be close to 275 lbs. But you are right, if you never rev the engine above 4000 RPM, there is no need for 93. But if you do, 93 octane has substantial benefits.
 
Curious to see the poll results on this once more owners chime in.
For those in CA, this is an easy choice given no one sells 93 octane.
Our options are usually limited to 87, 89, and 91
 
Jedi54 said:
Curious to see the poll results on this once more owners chime in.
For those in CA, this is an easy choice given no one sells 93 octane.
Our options are usually limited to 87, 89, and 91
Click to expand...
Ya...CA sucks for that and many other things ...even with brown gone we are still going to get the shaft! Notice your DVM bill lately?

ON TOPIC....
There is a couple things about boosted engines....NO ONE drive around all the time under boost! Therefore if 87 is a choice to safely use in the owners manual from the auto manufacture then you can use 87. If and I am sure you read the intent of lower octane it is not to be used under certain engine operations? The ECU makes engine operation changes that will allow the use of lower octane fuels that will still have the engine making plenty of power (up to a point). The MYTH about higher octane fuels is very strong on internet media even in racing we only use the octane needed to prevent pre ignition, other wise using higher octane fuel is not only a waste of money but many times you have to compensate changes using it because it burns slower then lower octane fuels and can cause some interesting AFR changes. Yes I said slower!
However peace of mind goes a long way so if some feel better about using 91 octane fuel then go for it. In a daily driver it is not going to harm anything except your bank account.
Now keep in mind if you drive your vehicle spiritedly often then by all means keep that tank filled with the highest octane available to you 91+!


We DYNO tested several cars a few years ago on a 65F degree day using 87 octane as per the auto manufacture and 91. Duplicating the test perimeters for each run there was no difference in engine output using 87 vs 91 except on a boosted engine making 18psi or more boost. The boosted engine did drop 5-9 HP on average and the torque levels lowered as well. (most people can not feel less then a 10HP difference in engine output) What we noticed was the timing,fueling and knock values change under boost more on ther engine with 87 octane under boost vs almost no changes with 91 octane fuel.

 
Jedi54 said:
Curious to see the poll results on this once more owners chime in.
For those in CA, this is an easy choice given no one sells 93 octane.
Our options are usually limited to 87, 89, and 91
Click to expand...

I've been putting 91 in my CX-9 (same engine) since I got it last year. I did try 87 for four or five tanks, oddly enough I noticed slightly less range traveled and a very minor decrease in "pep" once I'm at speed. I like the pep, so 91 it is. Helps that 87 octane is only 0.86c/L right now.
 
New CX-5 Signature and still on "dealership regular", but I will run Shell 87 in the future.
I did so during my entire ownership of a '16 CX-9 that has the same drivetrain.
Power was more than adequate for my use and I had the comfort of knowing that Shell is a Top Tier fuel with a superior additive package to keep the fuel system as clean as possible.

Compared to the traded '17 GT Premium, even with "dealership regular" I'm enjoying the Signature's inproved acceleration from a stop and when passing.
The CX-5 is my "practical" vehicle with great driving dynamics. I don't need it to serve as a sports car.
I have my MX-5 Miata to scratch the itch for pure driving pleasure. (drive2)
And yes; THAT car runs 93 octane. (burnout)
 
I'm not sure whether the industry has completely solved the carbon buildup on intake valves with direct injection, so for me, I use Shell 91 (highest in CO) because that one is Top Tier (lower octanes don't appear to be) and recommended by Audi. Another thing to consider is as engines age, there can be carbon deposits on the underside of the head, or piston rings. Either of these can be a source of pre-iginition, so again Top Tier for me. You might not ever notice, just a bit of timing retardation and lower power versus when it was brand new.

I don't know that comparing HP at low RPM is the whole story. Maybe HP is the same but the engine can advance timing with higher octane to get better MPG/HP? If so the only way to know the difference is a series of fillups and compare mileage and see if the price cost is worth it.

There must be significant gains to be made in higher octane or the auto manufacturers wouldn't be lobbying to get the octane changed accross the board nationwide. I was talking with our plant manager just recently and he said the biggest capital investment he see over the next 10 years is to raise octane, he hears the manufacturers want 95. Interesting times.
 
All grades of Shell are Top Tier.
Premium is just even more so with its additive package.
 
Last edited:
I have a local station that sells 90 octane ethanol free gas - for ~20 cents more than 87. I used it in my CX-5 occasionally and would see increased fuel economy. May give that a shot to see how the CX-9 handles that.
 
dougal said:
I have a local station that sells 90 octane ethanol free gas - for ~20 cents more than 87. I used it in my CX-5 occasionally and would see increased fuel economy. May give that a shot to see how the CX-9 handles that.
Click to expand...

I use Shell 91 "V-Power NiTRO+" mainly because it's ethanol free (in Canada) and because of the detergents. I've noticed a 50-60 km increase in total range compared to Shell 87. Your (literal) mileage may vary. :)

For anyone in the U.S. and Canada wanting to find out if ethanol free gas is available locally, start here: www.pure-gas.org
 
For those who have ethanol free in their locations:

1- is any of it big name brand?
2- what do you know about the additives in it?

Ethanol free is obviously better than ethanol blends in every respect, everything else being equal.

But is everything else "equal"?
 
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