Octane Rating - 2014 Mazda CX-5 Long-Term Road Test

2014 Mazda CX-5 Grand Touring AWD Long-Term Road Test

2014 Mazda CX-5 Grand Touring AWD: Octane Rating

March 22, 2013

2014 Mazda CX-5 Grand Touring AWD

The topic of proper octane for our 2014 Mazda CX-5 Grand Touring AWD came up recently. Since I had the car, I looked it up in the owner's manual. Of course, I found the familiar refrain:

[87(R+M/2) method] or above (91 RON or above)

What does it mean? It means you can put 87 or above in the tank. We're seeing this sort of "don't go below 87, but you can go above" language more and more. In fact, we even proved (here) that even if it isn't required, that running premium fuel can save you money, under the right circumstances and in the right car. "Your results may vary."

So, has anybody out there done this experiment with their CX-5? Did you find that the extra cost per gallon was offset because your CX-5 ran so much more efficiently and earned more miles per gallon?

Chris Walton, Chief Road Test Editor @ 3,504 miles


  • hopster hopster Posts:

    Chris- I think you misunderstood what the octane requirements says. In the US we use R + M (avg of RON and MON), in Europe they use just RON for their rating. MON usually runs a few points lower than RON ratings- thus whey R+M is lower on the spec. This spec is a catch all for USA and Europe. It doesn't make any mention of using anything above 87 octane here in the USA.

  • fordson1 fordson1 Posts:

    Well, I think it does say "regular or above" for both methods, but you can't weigh the cost/benefit ratio of premium by just talking about efficiency in terms of mpg. If the car gets better mileage, you are stopping to refuel less frequently (not by much but...), so it's more convenient, you are making more power, so that's a performance enhancement, and premium usually has a better detergent/additive package, so valves and/or other fuel system components stay in better shape. Now, comparing the Cruze or other FI car against the CX-5, which has a slightly higher than average compression ratio but is naturally-aspirated, is not an apt comparison. FI engines usually will return a lower cost-per-mile in terms of fuel economy alone when using premium, regardless of what the manual says, but I would doubt most NA-engined vehicles would. But as I say considering mpg alone ignores the other benefits as listed above.

  • bassracerx bassracerx Posts:

    im kinda wondering what a tank of premium fuel would do in my honda fit i already get above the epa estimated milage with just regular

  • texases texases Posts:

    For vehicles set up for regular, some will and some won't improve with higher octane gas. It depends on the mapping for the ignition system and know sensor. But it won't hurt to try.

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