Is it worth it to use premium fuel?

[02V70]

I have a 2.4l Turbo engine in my '02 v70XC, the manual says this

Volvo engines are designed for optimum performance on unleaded premium gasoline with an octane rating AKI of 91, or above. AKI (ANTI KNOCK INDEX) is an average of the Research Octane Number, RON, and the Motor Octane Number, MON. (RON + MON/2). The minimum octane requirement is AKI 87 (RON 91).

What are the advantages of using premium fuel? I have read conflicting information about it. Does it actually increase MPG? If so, is it enough to justify its higher cost? What kind of performance gain does it give? More horsepower?

[dikidera]

Increase mpg but pay more = same thing. The only way to truly increase mpg is to be gentle on the throttle and maybe lean out the afr.

[vtl]

I have a 2.4l Turbo engine in my '02 v70XC, the manual says this

Volvo engines are designed for optimum performance on unleaded premium gasoline with an octane rating AKI of 91, or above. AKI (ANTI KNOCK INDEX) is an average of the Research Octane Number, RON, and the Motor Octane Number, MON. (RON + MON/2). The minimum octane requirement is AKI 87 (RON 91).

What are the advantages of using premium fuel? I have read conflicting information about it. Does it actually increase MPG? If so, is it enough to justify its higher cost? What kind of performance gain does it give? More horsepower?

More power at full throttle. At least some power in hot weather. This mostly applies to turbo engines. N/A will be fine with 87.

[velorider]

This is a real good question. I don't believe the answer is more mpg or power. My understanding is high octane is a "more stable" fluid, when under high compression and heat there is reduced pre-ignition.

Our i5 have a compression ratio of 10.3:1. Is that high enough to cause pre-ignition under certain conditions and are you driving under those conditions. Either way it's not better gas mileage or horse power, but whether you're losing horse power and mileage due to pre-ignition not using 91.

[MoVolvos]

This is a real good question. I don't believe the answer is more mpg or power. My understanding is high octane is a "more stable" fluid, when under high compression and heat there is reduced pre-ignition.

Our i5 have a compression ratio of 10.3:1. Is that high enough to cause pre-ignition under certain conditions and are you driving under those conditions. Either way it's not better gas mileage or horse power, but whether you're losing horse power and mileage due to pre-ignition not using 91.

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The fuel is not more stable but just combust better. I remember driving with Leaded Fuel. Have used Supreme which is 91 in CA and 93 in NC. Never had a problem with CATS, Plugs and Injectors. Mileage was always higher and car ran much peppier and smoother. When the computer has to retard timing... You will put your foot down a little more to get what you would with Premium. Most of the time it's a wash in terms of cost to mileage but the car gets all the benefits beside your driving experience.
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[vtl]

The fuel is not more stable but just combust better.

Well, for the matter of fact, higher octane gas combusts worse (slower)

[dikidera]

The information I read is that higher octane fuels have more filler to absorb the heat that causes pre-ignition or detonation, not that the premium fuel has more energy density. However on my old S40 1.6 2003 the car had more oomph with lower octane fuels than premium(what we call 100 octane in Europe).

In the end from my understanding, the high octane fuel is probably for engines with higher compression ratios than our naturally aspirated Volvos, and the turbo versions can run on much less timing and reduce knock even with low quality fuel and still make power).

The reason is that higher octane fuel probably burns slower(i.e flame propagation) and thus will require more timing from a regular engine to run how it was before.

[MoVolvos]

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Years of usage on dozens of cars of various Makes and Models proves it's not only better for the car but also increase mileage besides peppier. Since the fuel burns more fully besides cleaner you do ease your foot on the accelerator for the same "GO" as lower octane therefore more MPG.

To name a few Makes owned using Premium - Acura, Toyota, Nissan, Honda, Lexus, Dodge Colt/Mitsubishi, Ford, Plymouth Grand Voyager/ Mitsubishi, Benz, VW and Volvo.
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https://www.scfuels.com/octane-fuel/

Does a Higher Octane Fuel Improve Fuel Economy?

Besides the environmental benefits, higher octane fuel also creates more energy per rotation than standard fuel. This characteristic may positively affect your vehicle’s fuel economy if you have a higher-compression ratio engine.

Is Higher Octane Better For The Environment?

You may be wondering what octane and fuel quality mean for your internal combustion engine (ICE)? Well, to begin with, higher octane has a very positive effect on the environment. By using up more of the fuel in the chamber less emission is produced from the ignition. More used = less released. A study from MIT in 2014 even suggests that higher octane fuels could cut our annual CO2 emissions by 35 million tons. Besides the environmental benefits, higher octane fuel puts out more energy per rotation than standard fuel meaning that your vehicle’s fuel economy is positively affected.
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[scot850]

if your car user manual tells you to use premium, then use premium. If it says you can use regular then use regular. When I bought my Toyota 4Runner V8, I was told by the dealer it ran on regular. Well, guess what?? Reading the user manual tells you run it on premium and not regular!

Regular makes the engine run hotter under load. We had a 93 850 NA. If I knew we were going to be running around town mostly (which we did), I used regular. If I was going to do any long runs on highways, I always filled the tank with premium.

We also used to have a distinction between regular and premium and that was the cleaners/additives they had. Regular usually had little or none. Premium had all the good additives if you believe the manufacturers. In recent years, some supplies now add cleaner to all grades so the distinction has become more cloudy.

I don't do a huge mileage a year, so using premium is not a huge expense and as I do shorter runs, I know the engine burns cleaner.

In modern engines with direct injection, you no longer get the advantage of intake cleaning from the gasoline, so fuel grade is less of an issue, the intakes get clogged no matter what you use!

So bottom line. In my world, if the manufacturer tells you to use premium, use premium. They designed it to run on it so use it or find out in time if that was a bad decision.

Good Luck!

Neil.

[velorider]

The fuel is not more stable but just combust better. .
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Your information in not correct. Instead of two idiots arguing something we are not experts in, I will simply site source from the. U.S. Energy Information Administration

https://www.eia.gov/energyexplained/gas ... -depth.php

Second paragraph:
"'Octane ratings are measures of fuel stability"

""These ratings are based on the pressure at which a fuel will spontaneously combust (auto-ignite) "

https://www.fuelfreedom.org/what-is-octane/

The short answer is that octane is the measure of how much compression a fuel can withstand before igniting. Or, in layman’s terms, the higher the octane rating, the less likely the fuel is going to pre-ignite (read: explode unexpectedly) at higher pressures and damage your engine

I could site hundreds more, that explain the same.

The site you quote is more marketing focuses than science but is does say what octane is in the first question.

"octane rating, which is the level at which your vehicle’s fuel will combust"