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- RDX Aspec Adv.
very simple... just like any other engine/car out there, the ECU's strategy to avoid/prevent/stop detonation under the right conditions (hot weather, high engine load), is to run the engine richer (increase injector duty cycle, reduce ignition timing)... since the SkyActiv is known to run in full closed loop ECU operation (knock sensor is utilized at all times), running high octane gas WILL allow the fuel mixture to be leaner, thus excess unburned fuel will not get "washed down" past the piston rings into the oil pan
oil analysis reports can be found on other forums that proves this
This guy used 87 octane, had 0.5% fuel on a 5,300mile interval. A non-issue, even addressed in the UOA from the lab.
https://bobistheoilguy.com/forums/ubbthreads.php/topics/4056275/Mazda_0W-20_moly_-_5,370_miles
This guy with a 2.0, DID notice that running higher octane reduced fuel %:
https://bobistheoilguy.com/forums/ubbthreads.php/topics/3536768/High_Fuel__2013_Mazda_CX-5_2.0
This guy has no problems (no octane listed):
https://bobistheoilguy.com/forums/u...16/2016_Mazda_CX5_2.0_7,898/12,97#Post4197416
This guy uses 87 octane. No issues:
https://bobistheoilguy.com/forums/u...50/2016_CX-5_Sport_2.0_6MT_5,073/#Post4178550
Nearly 9K miles on this UOA, no issues really, but there is discussion:
https://bobistheoilguy.com/forums/u...86/Mag1_Ow20_-_8,951_Miles_-_'16.#Post4167486
Long story short: If you change oil at 5K miles, who cares? If you like to do the 10K mile thing, yeah, you may want to consider running premium.