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A comment on How does a gas pump know to shut itself off? (1981). Parent comment

Re:How does a gas pump know to shut itself off? (1981) by tw04 on Saturday October 10, 2020 @07:06PM (#24742562)
Priming has nothing to do with cleaning. It’s higher octane fuel. If your car Isn’t designed for higher octane fuel it will run like garbage. The whole point of high octane fuel is that it requires a higher temperature to ignite. If your car Isn’t designed for it it’s most likely only going to partially burn the fuel.
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Re:How does a gas pump know to shut itself off? (1981) by kortilla on Saturday October 10, 2020 @07:11PM (#24742580)
No, the main point of high octane fuel is to be resistant to higher compression ratios so it doesn’t pre-detonate. Spark plugs have no issues igniting it.

What op is referring to is additives that are added in by some gas dealers to the high octane fuel to upsell you. “Techron” is one I recall seeing at Chevron IIRC.

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Re:How does a gas pump know to shut itself off? (1981) by pxx on Saturday October 10, 2020 @07:39PM (#24742732)
You can sometimes buy the additives separately. e.g. for Techron: https://amzn.to/33LH1RN
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Re:How does a gas pump know to shut itself off? (1981) by herdrick on Saturday October 10, 2020 @07:32PM (#24742703)
The parent comment is right. It's not just the spark; heat and pressure are also part of what ignites your air/fuel mixture.
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Re:How does a gas pump know to shut itself off? (1981) by kortilla on Wednesday October 14, 2020 @12:42AM (#24773143)
Not with gasoline. A gas engine can ignite at temps well below 0F and low compression.

You might be thinking of diesel. Diesel depends on compression to combust and has heater coils to ensure minimum temps as well.

This is more obvious when you read engine specs and they have minimum octane ratings, not specific ratings.

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Re:How does a gas pump know to shut itself off? (1981) by arghwhat on Saturday October 10, 2020 @07:18PM (#24742623)
High-octane fuels will not burn poorly. It just isn't necessary to increase octane further once the threshold of knocking/self-ignition at the target compression and cylinder temperature is reached.

Plus you missed the point: In many places the premium fuel is the same octane number as regular (e.g. 95), but premium is with additives for <insert vague marketing>.

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