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After making the change from 87 octane to 89, I could feel a significant improvement in performance when accelerating from off-throttle. Same petrol station. The mileage on my 2.5-liter non-turbo engine is 45k. Has anybody else had the same thing happen?

Nobody is surprised by this. Our engines have excessively high compression ratios for 87. In order to avoid knocking, the computer retracts. It usually happens at the beginning of second gear. The use of 89 produces remarkable results. For months when the temperature regularly exceeds 100 degrees, you may want to think about switching to 91. For me, this was monumental. Significantly more so than the discovery of the tire upgrade. Putting 89 octane and UHP 235/50R18 tires on this vehicle made a huge difference!

I understand now, so thank you.

The engine simply detunes to 227 horsepower, according to factory specs, so 87 octane is OK. Since January 2021, I have been driving my CX30 turbo with 87 octane and have never had any issues.

On the 2.5L, it's not the same. A severe hesitancy may occur at the beginning of second gear. My vehicle could really use 227 horsepower!

The proprietary friction modifiers in Shell Premium's additive blend help reduce engine wear and offset the effects of any oil-fuel dilution. I've always used it in my 2.5L NA CX-30 and now Mazda3. In comparison to other top-tier rated fuels, such as Shell Regular and all grades of Chevron, Shell Premium additive blend has the highest detergent level at 5 times the EPA mandated minimum. For a GDI engine to run smoothly and efficiently, it is crucial to keep the direct-injectors as clean as possible.

Similarly, Mazda's SkyActiv-G lacks port-injection but boasts an exceptionally well-planned GDI design to keep carbon buildup to a minimum in other engine parts to a minimum. In order to reduce the carbon buildup that is common in GDI engines, Mazda engineered the Skyactiv-G to have hotter intake valves. This helps to discourage the formation of deposits. To further minimize blowby, the engine uses high-efficiency combustion and has an air-oil separator built into the positive crankcase ventilation (PCV) line.

Great information, SDH. I was unaware that the PVC system had an oil-and-air separator. As for the carbon buildup on the intake valves, I've been quite worried about it. The engineers at Mazda are absolutely fantastic. Their automobiles are top-notch.

because of the high altitude, regular gas is typically 86 octane. Midgrade gas, which is rated 88, is something I've experimented with here. So far, no change has occurred to me. No one has ever tapped on my door. With the additional fifty cents per gallon for midgrade gas, I think I'll stick with regular gas. The general consensus is that using higher octane fuel is a waste of money unless you pay attention to knocking.