Questions tagged [octane]

A number relating to the ignition temperature of gasoline in a combustion chamber.

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2answers
103 views

How can my car run on 85 octane but be recommended to run on 91?

My manual recommends I use 91 octane, especially when at altitude or towing, but says I can get by on 85. To my understanding, the octane rating is a measurement of fuels tendency towards preignition, ...
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2answers
824 views

Smoother engine with lower octane

My manual says to run 91 or greater octane, so I've religiously run 93 octane Texaco gas. Recently I was low on gas and there were no gas stations around other than a 76 and they only had 91 octane ...
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1answer
491 views

High or low octane and mileage? [duplicate]

I understand that you want to use the octane that your car calls for. Higher octane cost more at the pump. Ethanol aside, are there instances in climate or the terrain where a shift in octane level ...
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292 views

Avante 2010 M16 GDI 1.6L Fuel Type

I own an imported Avante 2012 M16 GDI 1.6L from Korea (basicly an Elantra with extra options). The 400 page plus manual and all references on the internet are in Korean, so I have no clue what type ...
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2answers
1k views

Recommended fuel for Honda Fit Sport 2008

I recently bought a Honda Fit 2008, and I want to know what is the recommended fuel for my car? In my country the gas stations sell "Regular" and "Superior" gasoline. The Owners Manual recommends to ...
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2answers
8k views

Will 93 octane fuel burn completely in an 87 octane engine?

This is a little more specific than the "wrong fuel" question: I'm looking for the long term impact of using a higher-octane fuel in an engine designed for lower octane fuel. Not quite diesel in a gas ...
3
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1answer
1k views

Octane number definition differences in different countries

In United States, I have understood that octane numbers are generally lower than in Europe for two reasons. Firstly, the gasoline is often genuinely lower-octane. Secondly, the numbers in United ...
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0answers
16 views

How much can sub-optimal octane affect fuel economy? [duplicate]

Pick any production car that is factory-tuned for high octane fuel. We know that on lower-octane fuel it has to retard timing to avoid knocking. In effect, it has to run at a lower compression ratio....
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2answers
323 views

How much can sub-optimal octane affect efficiency or power?

Suppose a production fuel-injected engine is tuned for 93 octane fuel. As I understand it, the engine can still run on lower-octane (i.e., less knock-resistant) fuel, but it will pull timing to avoid ...
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0answers
80 views

About Hyundai Atos 1998 1000cc fuel

What is the right octane number of fuel suitable for car Hyundai Atos 1998 1000cc, 80 or 92?
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5k views

Changing spark timing to use a lower octane fuel?

Recently in Egypt, gas prices went up by a lot. We have three octane ratings here: 95, 92, and 80 RON. (I am not sure how 80 is so low; maybe it has lead in it?) Most of the cars here are supposed ...
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2answers
377 views

Does petrol gradually get a higher octane rating with evaporation over time?

One thing that is keeping me busy, is that my car seems to react different after I have filled up at the petrol station. I fill it up with 95RON. It seems to be a little more aggressive, but it sounds ...
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2answers
168 views

Lexus RX200t octane

I have a new Lexus RX200t which is now at 10k miles. I have been purchasing 98 octane gas but considering moving to 95. Is this recommended? The manual says 95 is ok but I'd like to hear what experts ...
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2answers
4k views

Can mixing octanes cause the check engine light to come on?

A Nissan Versa (2008 or '09) driver in the USA, running on 87-octane usually, decided to fill up from almost-empty on 89-octane based on advise that it helps clean the engine. They returned to highway ...
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2answers
775 views

85 octane gas causing engine knocking and retarded CAM time?

I'm about to betray my ignorance of cars but here goes: I am a driver from Minnesota (where the lowest octane rating is 87) vacationing in Colorado and have noticed that after I put 85 octane ...
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2answers
2k views

Fuel Type (octane) for Mazda Axela 2010

I bought an imported (from Japan) Mazda Axela 2010 (i-stop, 1990cc, sedan) and the dealer asked me to use 95 octane petrol. There are a lot of misconceptions about octane and I heard many dealers ...
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6answers
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Should I use gasoline 87, 89 or 93 on 2016 RAV4 SE

I read many articles online and people have different opinions about this issue. Some say 89 is the best for acceleration. Others say 87 is just fine. I'm worried only about the health of my car. ...
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1answer
285 views

Is it fine to use higher octane gasoline than what is recommended on the fuel cap sticker

I've got a 2000 W202 Mercedes C240. It's got a V-shaped, six cylinder gasoline engine. On the fuel cap, it says RON 95 EN 228. And in the manual also it says "Use only Premium Unleaded petrol". I ...
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1answer
175 views

What grade of fuel should I use for my car? [duplicate]

I have a 2006 Volvo XC90. The manual says that the recommended fuel is 91 octane, and the minimum is 87. I found a forum thread with people recommending various things, but the consensus seems to be ...
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1answer
8k views

Premium vs. regular in medium compression engines

We probably all know that using premium grade gasoline in a low compression engine (less than 9.5:1) is nothing but a waste of money, but what about medium compression engines with a compression ratio ...
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1answer
66 views

Gasoline grade manufacturer recommends vs what was used during testing

Toyota recommends to use regular(87) grade of gasoline, but tested cars with the gasoline grade 91(see user manual). Somebody know why they recommend to use grade 87 if they did not tested cars with ...
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1answer
105 views

How can I tell if I would benefit from higher octane fuel?

Given the number of variables involved in whether an engine will knock on a given fuel in a given environment: How can an end user determine whether the engine is retarding timing due to fuel octane? ...
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2answers
1k views

How often does my engine check fuel octane?

I have an Acura TL, which specifies "premium" fuel. However, I know that the engine has anti-knock sensors that retard timing to prevent detonation if somebody accidentally fills it with lower-octane ...
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2answers
200 views

Is it a good idea to top off the gasoline with higher octane fuel in a specific case?

When topping off the gasoline in a vehicle that is rarely driven (100 miles/month), is there any advantage in topping it off with a higher octane gasoline? I've heard stories that the octane of ...
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2answers
13k views

Switching to a higher octane

This may be a very noob question to ask. But I recently got this car and was used with 92 octane petrol. However, to my negligence I overlooked the user manual which states to include 95 octane petrol....
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1answer
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How much Octane Fuel does Honda CBR 250R (India Version) needs? 91 or 93?

Honda CBR250R STD 2013 Model's manual state that fuel(petrol) used should be 91 or more. Seems like they have defined the minimum threshold of RON than stating the optimum RON for the given bike. ...
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2answers
173 views

Toyota Sprinter does not specify octane rating

I have recently acquired a 1999 Toyota Sprinter (Japanese domestic import). I realised that the engine "ping" so someone recommend to use 90 Octane petrol. I went through the manual but it only says "...
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5answers
78k views

Can I use lower octane fuel at high elevation?

Here in Colorado, gas stations sell "regular" gasoline which is rated at 85 octane ((M+R)/2). In most of the rest of the US, 87 octane is the lowest grade available. (As noted previously, higher ...
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4answers
3k views

Is it feasible to Turbo a NA engine while maintaining 87 AKI octane fuel use?

I have a Honda Civic with a naturally-aspirated Honda D17A2 (9.9:1 compression ratio). Goal: I want a modest horsepower gain (say +38 hp) in the lower-mid-range powerband; I'm not after the maximum ...
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9answers
118k views

Will higher octane fuel improve gas mileage?

I've heard from some people that high octane fuel will increase gas mileage. Around here, we have the basic unleaded(87), mid-grade(89), and premium(93 or 91). I've been using the basic 87 unleaded ...
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8answers
25k views

When given a choice between octane 89 and 93, which should I choose?

I just recently got a 2005 Volvo S40 with a turbo engine; I want to take good care of it, so naturally, when the instruction manual recommends 91 octane fuel but says it takes a minimum of 87, I have ...
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4answers
12k views

Difference between high octane and low octane?

What is the difference between high octane and low octane fuel? I'm not asking if one is better than the other for my vehicle, specifically, but rather what occurs differently both scientifically and ...
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3answers
12k views

Static vs. Effective compression: Why does higher effective compression not require higher octane gas?

Background I've been trying to do a lot of research on boost lately because I'm planning on running a moderate turbo setup on my daily/light-duty-autox car in the future. I'm trying to get into the ...
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10answers
43k views

What are the benefits of premium (high octane) petrol?

Here in the UK it's common for petrol (gas) stations to offer both regular and "premium" unleaded petrol. The premium stuff is (naturally) more expensive, and I've often wondered what the actual ...