What grade of gasoline do you use?

[kidulan]

This is what "I think" or "my 2cents"

After reading the forum and do some research on 87 vs 91 octane from Google (my best knowledged virtual friend), here are my conclusions:

1. Some people claim that 91 octane gives slightly better MPG, it sounds right to me because 91 octane gives more power and technically it increase the distance / paddle. 375hp > 365 hp ==> 375hp should run slight farther than 365 with same amount of gas / accelerate. (of course we need to ignore some other factors like weight, wind, slope....)

2. Manual says V6 runs 87 or higher, V8 runs 87 or higher to get better performance. that means do whatever you like (either few bucks save or more HP fun)

3. To Me, I got V6 and I run 87 octane that save me more than USD$100 / year and I will spend some bucks to buy Chevron cleaner (dont' know name) to make my engine/tank much more clean than using 91 octance for whole year.

4. In canada, it is about 37.5 cents (USD) difference per gallon between regular and premium. Damn it. ( 3.47 USD / Gallon vs 3.85 USD / Gallon when price in gas station is cheap )

5. But if I got the V8 Model, I might use 91 Octane instead of 87 Octane.

6. If you are running with 91 Octane and wonder why some people want to run with 87 octane, ask yourself why not 93/94 but 91? (this example might not be appropriate but I like this example)

Thanks for reading.

 

[medhat]

Im running 87. Since there has been scientific data that points to more power for the V8, i'm gonna try it out to see if I can tell the difference.

I'm running that experiment now, and so far I don't think I'd know the difference (it it was actually a "blinded" experiment, but then again, driving with a blindfold might be concerning). Given that the days of low-octane "knock" thankfully don't pertain to the Genesis (much less any other cars), I really didn't expect to notice a difference, and the marginal increase in horsepower is probably not relevant to me in the day to day.

 

[TJPark01]

I'm running that experiment now, and so far I don't think I'd know the difference (it it was actually a "blinded" experiment, but then again, driving with a blindfold might be concerning). Given that the days of low-octane "knock" thankfully don't pertain to the Genesis (much less any other cars), I really didn't expect to notice a difference, and the marginal increase in horsepower is probably not relevant to me in the day to day.

Yeah, I'm not expecting much. Can you tell the difference between regular tofu and organic tofu? Nope, they both taste like cardboard.

 

[wincrasher]

If I understand correctly, the energy value of 91 octane is the same as 87.

91 lets the computer advance the timing slightly and that is how you gain extra power.

 

[ImInPA]

If I understand correctly, the energy value of 91 octane is the same as 87.

91 lets the computer advance the timing slightly and that is how you gain extra power.

The energy value of 87 octane is higher than 91 octane. The higher octane does not ignite as easily as the lower octane grade. The additional "power" from the higher octane is due to the ECU being able ti adjust the timing to allow a higher compression cycle without the risk of pre-ignition (dieseling) and knock.

 

[bnajack]

I normally use regular unleaded as I cannot tell the difference in power between it an premium. I check my mileage on every tank and I "think" I get about 1 mpg better using premium.

 

[Mark_888]

Sorry, had a gas comment, but had deleted it editing my digression.

Don't think that MPG would go up with higher octane. No technical reason why it should. I'd think it would go down actually, if you are putting out more HP.

But for a given speed, you are using less fuel for the same horsepower, so the higher octane fuel can produce better MPG if the engine ECU is designed to adjust the timing to increase the compression ratio.

 

[Mark_888]

If you are running with 91 Octane and wonder why some people want to run with 87 octane, ask yourself why not 93/94 but 91? (this example might not be appropriate but I like this example).

When a manufacturer designs an engine with variable timing that will increase the compression ratio for more horsepower with higher octane fuel, that does not mean that this works indefinitely for any octane. They only do it for a limited range of octane ratings, and once you reach a certain level there is no advantage in going higher unless they modify the ECU and also make the engine robust enough to handle the higher compression ratio.

The same applies to an engine that is only designed to use 87 octane and will not benefit from higher octane because the ECU is not designed with variable timing for higher compression ratio. Of course, if your engine is pinging, then you may need to use higher octane for other reasons besides more horsepower and better MPG.

Also keep in mind that octane requirements are actually not "fixed". In high altitude cities like Denver, regular grade fuel is 85 octane and premium is usually 89 octane. Probably not too many Genesis owners from Denver because rear-wheel drive cars don't sell well there (it is not practical to run snow tires in the winter in Denver because roads are only occasionally snow-packed because of the intense sun, but when they are snow packed you don't want rear-wheel drive).

 

[Kevinc5a]

Magnets mates, magnets.

 

[SterlingDave]

Also keep in mind that octane requirements are actually not "fixed". In high altitude cities like Denver, regular grade fuel is 85 octane and premium is usually 89 octane. Probably not too many Genesis owners from Denver because rear-wheel drive cars don't sell well there (it is not practical to run snow tires in the winter in Denver because roads are only occasionally snow-packed because of the intense sun, but when they are snow packed you don't want rear-wheel drive).

Good points, Mark, but there is another solution to the winter driving here in Denver. We've taken to heading to Arizona for the winter.....I expect that my gennie will do quite nicely down there.

Oh, and for when we get caught here in the snow we just use our old heavy cruiser, a 4wd Suburban.

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[Rey]

I have been running 87 octane since new with no audible knock/detonation issues. My understanding is that 87 octane contains more energy than 91+ octane. I am sure there is an engineering paper out there that confirms this. I had a Cadillac CTS-V, a car with similar compression ratio and octane requirements. I consistently got better mileage using 87 octane on highway cruise.
No doubt that aggressive acceleration will cause the motor to sense pending detonation and retard ignition. Retarded ignition will reduce gas mileage. That's why I often got better gas mileage in town with premium. There was less ignition retard on premium. But on simple highway cruise with very light throttle adjustments there is little or no such retardation. This was easily confirmed with a ScanGauge, which I have mounted on my dash.
Another factor to consider is freshness of gasoline. Gasoline does degrade over time, hence products like Stabil are sold. 87 octane gasoline is often "fresher" than premium grade simply because more drivers buy 87 octane. When traveling I tend to frequent gas stations which do a lot of business because the likelhood that their fuel is a bit fresher.

 

[wilmoth]

I alternate every other fill-up. I seem to notice a little get up and go on the high octane.

 

[mgust]

Guys. When purchased, the dealer filled the tank of my 2010 Genesis 4.6 with regular. I was disappointed but it ran just fine. Since then I have variously run all three grades. I cannot document a savings in gas mileage between regular and premium, but I can tell unquestionably what grade is in the tank under hard acceleration. I haven't heard any pinging with regular. So my mood dictates the grade I buy. Incidentally, the car loves Shell gas a lot.

 

[bigel]

I have used 87 octane exclusively in all of my cars over the past 26 years; I guess I've never had enough spare cash so as to become ambivalent to spending $6.50 more (on average) per fill-up. Even when fuel prices were down. To our friends north of the border, I realize that we in the U.S. have the luxury of supressed petroleum prices...

The difference in performance/fuel economy brought by running premium fuel has never been demonstrated to the extent that I'd consider it.

Now, the difference between conventional and synthetic lubricating oil is a far different story. I have been running 'Mobil 1' for the past 15 years and I swear by it. My last car had 198,000 miles on the engine with no major repair issues (timing belt @ 90k, head gasket ~ turbo engines tend to pop them more often than others).

How about the rest of you?

 

[robthoke]

I've been running premium on both of my cars. I also may not leave the house for days and the cars sit. So I may fill up about twice per month. Changing what I use is not really going to change my budget.

 

[OldSpice]

Even with a company gas card I almost always use 87 octane.
Once in a while I put 89 in, but I can't see any difference.
Most of the time I drive like everyone else, no need to race.

 

[msitter]

I only fill my tank 2-3 times per month so I have always used 93 oct. I do however always buy ethanol free fuel and since I have done that I do notice better mileage and running. There is a website, www.pure-gas.org, that lists every known station that sells ethanol free fuel. All my other power equipment, boat, motorcycle, cars, lawn equipment, generator and garden tractors run better and the fuel is more stable in winter than the E10 blend. The cost is the same as E10 or sometimes cheaper because the stations that sell it tend to be the discount and independent brands.

 

[Chief]

93 octane.

 

[Stoofpilot]

I consistently see 3 miles per gallon more with 93 vs 87 octane. This is approx 60 more miles out of the same tank size. This is about 2.4 gallons of regular required to give me the same number of miles. To me, the extra dollar per gallon for 97 is a wash considering the added distance per tank with 97. I also notice the difference in acceleration.

 

[robthoke]

I only fill my tank 2-3 times per month so I have always used 93 oct. I do however always buy ethanol free fuel and since I have done that I do notice better mileage and running. There is a website, www.pure-gas.org, that lists every known station that sells ethanol free fuel. All my other power equipment, boat, motorcycle, cars, lawn equipment, generator and garden tractors run better and the fuel is more stable in winter than the E10 blend. The cost is the same as E10 or sometimes cheaper because the stations that sell it tend to be the discount and independent brands.

Thanks for the info. I went to that site. There is only one station in my area that is ethanol free. I'll have to check them out. I'm surprised at some of the cities that are not on that list.