Is it cheaper to fill up with 87 gas and add an octane booster to get to 91 or 93, 94?

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regassert6@reddit

What kind of car? Odds are, you can safely run 87. You might get less mpg and reduced performance, but in many instances, the mpg reduction is less than the $ saved and the performance losses are negligible.

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IWillAssFuckYou@reddit

Is knocking not a risk?

I'm a V8 Camaro owner. I know if I were to accidentally put in 87 instead of 93 (what we have here since we don't usually see 91) I know it's not the end of the world because I see people in the forums make this mistake all the time and we always end up having to reassuring them it's fine, just run the tank down and refill with 93 at quarter tank, just don't drive the car hard with 87.

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IAmAThug101@reddit (OP)

Tercel. But I’m trying to pass smog. They said run 91, so Msybe adding booster gets to 93

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R87FX@reddit

I don’t think a higher octane will help pass smog. But if you are going to try anyway, just buy higher octane gas.

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IAmAThug101@reddit (OP)

Higher octane gas is harder to combust. Less combustion = less emissions.

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CaptainHubble@reddit

That's not how it works. High octane fuel is just less prone to pre ignition aka knock.

You need it on high compression engines. Otherwise you don't. It doesn't harm your engine if you use it, but you effectively paying for a feature of the fuel your car isn't even able to use.

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Maddad_666@reddit

In fact harder to burn may mean you have unburned hydrocarbons and thus worse emissions. Use 87.

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trix4rix@reddit

It isn't harder to burn, the adequate compression and spark ignites it exactly the same.

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Dangerous_Echidna229@reddit

You don’t want it to compression ignite, just spark ignition.

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Dangerous_Echidna229@reddit

No it isn’t.

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deeper-diver@reddit

*face palm*

If that's what you really think, just put diesel in there. That stuff will be even harder to combust in a gas engine. /s

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Chemical-Dig7065@reddit

Not how it works but also, less combustion means more missions cause un burnt fuel goes out the exhaust

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bemenaker@reddit

You will have higher emissions

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finalrendition@reddit

Tell that to diesel

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MEINSHNAKE@reddit

You must have been huffing that there 91 octane.

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Chesterrumble@reddit

High octane fuel will not help pass the smog test.

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Suitable_Boat_8739@reddit

Depends. I would think running lower octane than the car is designed for could result in higher emissions. Would only matter if the catalyst is already on its way out any your on the edge of passing

If the ECU is enriching air fuel and retarding timing to prevent knock im sure CO and hydrocarbon emissions will go up. If the ECU doesnt make much ajustment there might be a little more NOX (remember lower octane burns faster). A good catalyst should clean that all up but it would likely need to work harder.

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SpikeHyzerberg@reddit

advance the timing to pass.

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regassert6@reddit

how much have you spent on higher octane fuel so far? Why not just get the cat replaced?

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IAmAThug101@reddit (OP)

Nothing. I dont think it’s the cat. It passed at 25 mph.

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HoodGyno@reddit

it’s not the gas lol take it to a shop for a diagnosis

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Puzzleheaded_Sky4132@reddit

The difference between regular and premium is negligible. Even your example of 60 cents higher - if you bought 10 gallons of gas we’re talking about a $6 difference here

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TheKingOfSwing777@reddit

Twice a week that adds up for some people.

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tblax44@reddit

If $12 a week is hurting someone's budget that bad, they probably shouldn't have bought a car that requires premium

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TheKingOfSwing777@reddit

Sometimes people in that position don't choose their own car. For instance, I gave my sister a car that requires premium. Though I'm sure having an extra $50/month would be helpful for a full-time student, receiving a free car upfront is even more helpful.

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Red_Liner740@reddit

Depends on the price difference between 87 and 91. In US. No. In Canada, I did the math and it is cheaper. But that’s because gas stations increase premium price by 60c a liter. That’s 2.28 a gallon. 20 gallon tank makes it 45.60 per fillup difference. Can of octanium is $24 and will bump that 87 to 94.

I just keep my turbo coyote on e85 all the time with how little I drive it in the summer.

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Rlchv70@reddit

Octane booster increases octane by “one point”. One point is 0.1. So one bottle of octane booster changes 87 octane to 87.1.

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Red_Liner740@reddit

Maybe that crap at gas stations. Octanium most certainly raises it by full points. Coyotes knock hunt and will advance timing. My friends car picked up 6 mph in the 1/4. 2015 supercharged Mustang.

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spokismONE@reddit

This is only true for the shitty octane booster they sell at gas stations.

A 32oz can of Torco or VP madditive can turn 8 gallons of 93 into a real 101 octane.

Still cheaper to just get 93 in op’s case tho. A can of torco is like $30 now

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Fight_those_bastards@reddit

Unless you’re going full on batshit and mixing your own additives in. Xylene will definitely boost your octane substantially.

Note: don’t do this unless you really know what you’re doing.

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atljar@reddit

E85 is cheap octane!

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IAmAThug101@reddit (OP)

How? 85 is a lower number than 91

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DIY-exerciseGuy@reddit

Octane booster does basically nothing

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Glorious_Bastardo@reddit

Unless you’re running a forced induction engine (turbo or supercharger) or have a high compression race engine, you’re just wasting money by using high octane gas.

High octane gas simply helps prevent engine knocking. Which high compression engines or forced induction engines need to prevent destroying themselves.

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Blu_yello_husky@reddit

The 91 octane in my area is nonoxy, which is why I go for it, not because it's 91 octane. So, if the it's the same case for you, I would always choose 91 because you're not just paying for the octane boost, but you're paying for reduced engine contamination by not running corn gas and gumming everything up

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