The CX-5 is the only car/SUV I have owned where the customer gets a choice on those 3 levels of gas to be used - depending upon the hp desired. On my last few Audi's premium was required. On my wife's Subaru, suggestion is to use regular.
Questions - how would a car be able to vary the required octane levels without a noticeable drop in performance and engine wear? What are you guys using on your CX-5?

 

Let me know what you do. For my WRX I use Sunoco 91 octane, I don’t pay for the 94

I was going to do the same for wife’s turbo CX 5
I am in Virginia

 

With almost any car you have a choice of which octane to use. No one is making you use any particular octane, right? A recommendation is just that, a recommendation.

You don't say but I'm assuming that you have a turbo CX-5? If not, you're wasting your time and money messing around with difference octanes. Of course, it's yours to waste if you like...

In general the higher the engines compression ratio the greater the need to control preignition (aka knock). This is done with octane, the higher the octane the more control over preignition.

Some cars can take advantage of the higher octane to make more power by varying the timing, some can't. In some cars it's a total waste by using higher, and more expensive octane.

I use the lowest octane of 87 in my CX-5, that's what Mazda recommends. In my MX-5 Mazda recommends high octane, as the engine has a high compression ratio, and that's what I use. Kawasaki recommends using high octane in my motorcycle because of the high performance/high compression ratio and that's what I use.

Some people claim that they can feel the difference by using high octane in a car that doesn't require it. Maybe they do maybe they don't. Is it worth the difference?

YMMV

 

What does your manual say?

 

Thank you!
Yes, I have the turbo engine. Am I to assume you do also?
Of course no one is making me use a particular grade of gas. I always follow the recommended grade on all my cars I ever had. Again, on my 3 Audi's - premium was recommended - on my wife's 2006 Outback it was regular. So, looks like if someone wants more power/higher performance use premium, if not save the coin and use regular. Is switching between the 2 grades something that in any way negatively affects the overall longevity - if that's' the correct word of the engine?

 

For most average day to day driving, you'll likely not notice a huge change.
As a side note, most of the mid-grade level fuel has been replaced by E15
around here, though I haven't check all stations.
try a fill up of regular and see if you notice the difference.


My 2¢

 

I have always hated the terms used for gasoline like mid-grade. LOL
Those terms I think were generated in the 50's? lol
Really do any of you think that the quality is less then a higher octane level?
You look at the octane rating and how it was formulated.
Then what is an "average" driver? lol


I tried 87 octane for testing purposes on my 2.5 MAZDA 3 2018 , all performance levels (DATA LOGGED all the testing) went down! The MPG remained close enough the same as long as it was only me in the car 1/2 tank or full and close to level driving. I did not test with added weight or variable driving conditions. On the DYNO using 87 octane the power dropped out so much I am wondering how MAZDA ever claimed what they advertised? Repeating the DYNO with the DELTA set for the 91 fuel the power levels went back up to close to MAZDAs fairy tail output advertised!

 

Dennis,

Actually the dealership filled it with regular - said they ain't allowed to use fill a new car (at least this one anyway) with anything else.

 

I guess some of where my confusion is that Mazda states that for the CX-5 AWD TURO you get:

HORSEPOWER WITH 87 OCTANE PREMIUM UNLEADED FUEL 227
TORQUE WITH 87 OCTANE PREMIUM UNLEADED FUEL 310 lb-ft @ 2,000 rpm

HORSEPOWER WITH 93 OCTANE PREMIUM UNLEADED FUEL 250
TORQUE WITH 93 OCTANE PREMIUM UNLEADED FUEL 320 lb-ft @ 2,500 rpm

 

Hope he didn't hurt your leg when they pulled on it.