I just got my first Mazda. It's a CX-5 and I love it. I've always burned Premium because of the better performance and keeping the injectors clean and I generally get better fuel mileage.
I know the book calls for 87 Octane but was wondering if any of you burn anything higher and if you burn higher do you get better performance?
Also if you put a K&N air filter on is there any power or mileage improvement there?
Thanks.

 

A few comments:

• Premium fuel will not under any circumstances give better fuel economy unless an engine is designed to take advantage of the extra detonation resistance (typically via higher compression and/or timing advance).
• Premium fuel actually has slightly less BTU content per unit than regular (in other words, in an engine designed for Regular, using Premium will cause a reduction in fuel economy).
• In some instances Premium may have some more detergent, however, the extra detergent is effectively irrelevant as all fuel sold in the U.S. and Canada meets the most stringent requirements of the vehicle manufacturers.
• Assuming you are running a modern fuel injected engine, it is physically impossible for a K&N filter to improve fuel economy; said another way, regardless of whether you have a dirty factory filter, a clean factory filter, a K&N style filter, or for that matter, no filter at all, there will be no difference in fuel economy.
• If you put on a K&N, you may eek out a few extra ponies up near redline at wide-open-throttle, but those extra ponies will come at the expense of letting a lot more crap into your engine as K&N filters aren't much better at keeping dirt out of your engine than having no filter at all.

 

 

Highly unlikely; Mazda spent many-many millions of dollars on the SkyActiv engines to eek every ounce of power and economy out of them. Short of an expensive custom turbocharger application and an additionally expensive tune, there really isn't much you're going to accomplish. The above said, looking at all of the SkyActiv models over the last four or five years, it does look like Mazda engineered the engine bays with more than enough space to accommodate the 2.5T found in the latest CX-9 and the new Mazda6 turbo. If you can find a wrecked version of one of those cars, a swap might be kind of fun.

 

 

Thank you.

 

Both the 2.0l and 2.5l engines have 14:0:1 compression ratios which with variable valve timing, knock sensors and other skyactive magic allows them to run on regular gas. That being said, I run all my vehicles on non-ethanol unleaded gasoline. It comes in grades of 89, 91 and 93 pump octane. In the CX-5 I have used the 91 octane from day one. On long trips I have had to re-fuel with 87 octane ethanol fuel and my gas mileage goes down (ethanol) and the "quick/pep" disappears. I figure with higher octane gas it runs a little cooler and the engine itself doesn't have to compensate for the detonation of 87 octane at 14:1 compression. JMHO.