Comments by "Son of None" (@SonOfNone) on "Premium gas vs. regular: What's really better for your car? (CBC Marketplace)" video.

Higher octane fuels are only required in vehicles with higher compression ratios, as lower octane fuels will detonate prematurely [during the compression stroke]. Premature detonation [or knocking] not only means poor performance, but can damage the engine.
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@wolfpackflt670 Well said.
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@ryurc3033 Timing isn't the issue. The issue is the compression ratio. Higher compression ratios will detonate lower octane fuels during the compression stroke. No vehicle that I'm aware of has a variable compression ratio, nor one that a computer can alter.
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@drapermike Don't confuse octane rating with quality. If you have a new car and the manufacturer recommends regular 87 octane, then use that. Using a higher octane rating fuel will not keep your valves/internal components cleaner. Making sure you perform regular maintenance and having working sensors [o2, MAF, MAT, etc.] will make sure your fuel is properly combusted and not leaving carbon to build up.
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@larryhouse3776 I think that might be a bit misleading to say lower octane "burns better" on account that diesel fuel has a very low octane rating, and yet gasoline/petrol is much more flammable. I don't imagine there's much difference in flammability between 87 and 91 octane fuel, but 91 will definitely resist detonation during the compression stroke better, as you expressed. Otherwise, I entirely agree with you.
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