Gas regular or premium???

[Frnchy]

The dealer and the commercial tell you to use regular gas, but the owner's manual recommends premium.
Any suggestions?

2010, Genesis, 3.8, premium navigation, Titanium Gray Metallic

 

[MrB0462]

Either work just fine. IMO no particular reason to pay extra for premium. I regularly get 28-29 mpg with regular on trips. I have seen no real difference using premium, so I decided to spend my money elsewhere

 

[scottdk]

There are many other threads about this, but in the V6 regular is perfect and the V8 another 7 HP is gained by using premium and others on the forum including me report better fuel economy using premium and that it actually costs less due to the fuel economy increase with premium in the V8.

 

[wallymn]

premium without Corn if possible.

 

[BacktoHyundaibychoice]

For a $40K car I don't mind spending an extra $100-$150 a year to use premium.

 

[scottdk]

premium without Corn if possible.

I 2nd that

 

[MichaelOne]

I think I got an additional 1 MPG using premium vs. regular. No noticeable effect on performance.

 

[wallymn]

using premium without corn (still available here if you look) nets about 15% better fuel economy which pays for the price premium....

 

[iqjumpuw]

I was told to put regular gas in 3.8L V6 and premium in 4.6L V8.

 

[JimInNashville]

Regular. 22+ miles per gallon in mixed city/highway driving.
Tried premium, saw absolutely no difference.
The car is engineered to run on regular.

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[thom000001]

FYI....no car in the US is tuned for Premium from manufacturer.

All cars have to be able to run on crap Cali gas (max 91 octane). So the ones that say premium are actually referring to 91 octane...even for the few that have stickers for 93 near the fill. Its just a precautionary thing to help prevent detonation if you get a "bad batch" of fuel.

That being said, if you have a FI car (forced induction....supercharged or turbo) I would run 93 regardless.

In our cases, 87 has been prefect for me.

Tom

P.S. - 93 can make lots of power if tuned for it and forced induction for smaller motors..my previous G35 had a built motor, cams, and turbos and made 750bhp on 93 octane!

 

[msitter]

I use premium all the time and mostly use fuel that is all dinosaur. If you go to www.pure-gas.org you can find a list of ethanol free fuel. It does not cost any more than the diluted stuff and returns a good 8-10% better economy and will make your fuel system live longer. Pure gasoline does not spoil as quickly for those who have to store yard equipment, boats, motorcycles over the winter.

 

[jpfx]

new 3.8... first tank was regular, mpg was pretty poor and pulling away sometimes was harsh. i've put mid grade in now and seeing some improvement in both mpg and snatchiness on the accelerator.
That's the impression anyway, we both need to clock a lot more miles.

 

[QuantumRift]

Take for example, the "Smart for 2" car. It runs on PREMIUM fuel and gets the economy it gets from that fuel (E10 or not, all cars sold in the US are mandated by the government to be able to run on at least E10). The president of SMART went on the record saying that you can run mid range or regular in that engine but the economy and performance will suffer. And it does. An engine that can run on premium does so because of it's compression ratio and other design factors of the engine. If it is designed to extract the most energy out of a that fuel, it will do so. If you use regular, 87 octane, the engine's knock sensors will inform the CPU that the timing needs to be retarded, and the injector mapping will change, etc to accommodate. Thus less economy and less performance. The engine needs fuel that is slower burning (higher octane) to fully extract the BTUs from busting the chemical bonds during combustion.

As for E10, as I noted above, the government mandated a long time ago that all vehicle engines sold in the US after the mid-90's be able to run on E10. They also mandated that fuel be blended with E10. E10 does NOT destroy your fuel system (especially in new cars - they are designed to run at least E10 and many are E85 capable). Your fuel economy does not significantly suffer with blended 10% ethanol.

That means that with a 10 gallon tank, which would have roughly 1,140,000 BTUs available for energy (10 gallons x 114,000 BTUs per gallon of pure gas), you subtract ONE gallon, or 114,000 BTU, which leaves 9 gallons with 1,026,000 BTU. Now replace that gallon with one gallon of ethanol, at 76,000 BTU, and your 10 gallon tank now has less than the original 10 gallons worth of BTUs, but still has 1,102,000 BTU. Calculating the percentage yields 96.7%. So if your engine was giving you, say 50 miles per gallon on 10 gallons of pure gasoline (500 miles), with a 10% blend you'd go a bit less at 48.3 miles per gallon (483 miles). That's not a big DROP in economy and can probably be compensated for by changes in driving habits alone.

But I digress. I have been doing a lot of searching and reading on BUTANOL. Butanol is an industrial solvent....but look closer...it is more 'exciting' that ethanol, for sure. "Pure, unadulterated gasoline" being available for 'road use' is going to be a thing of the past. I have checked the "pure gas" site and the only stations that sell 'pure gasoline' are hundreds of miles away from me (I'm in SE Arizona). Not good anyways. You can get 100% gasoline at marinas and airports, but those fuels are not taxed for road use and cannot be legally introduced into your fuel vehicle's fuel tank. But anyways, let's get back to BUTANOL... it's a SECOND-GENERATION natural follow-on to ethanol..."Biobutanol or biobased Butanol has a higher energy density and lower volatility than ethanol.


if you can make ethanol, you can make butanol....AND there's already lots of research going in that direction. It's fairly common knowledge butanol can be made from the same (biomass) feedstocks as ethanol and used in an unmodified engine. Which here, probably means CORN in the short haul...And it does not take much to convert existing ethanol distilleries over to butanol. And it too, can be made from algae. Swiss company, Butalco GmbH, has a technology to modify yeasts in order to produce butanol instead of ethanol. Yeasts as production organisms for butanol have decisive advantages compared to bacteria. The company Gevo, Inc., in Englewood, Colorado, is developing a biotechnology process to mass-produce isobutanol from renewable resources." Plans are underway to market a fuel that is 85% Ethanol and 15% Butanol (E85B), so existing E85 internal combustion engines can run on a 100% renewable fuel that could be made without using any fossil fuels. Because its longer hydrocarbon chain causes it to be fairly non-polar, it is more similar to gasoline than it is to ethanol. Butanol has been demonstrated to work in vehicles designed for use with gasoline *without modification*.

This is a true biofuel for masses with potential of little or no impact on food supply and ability to compete favorably with $80+ bbl oil prices. Effort is focused on both fermentation of sugars, starch and other biomass and through pyrolysis and reformulation of biomass.

So it may not be "regular or premium" but gas or biobutanol??

 

[CARguyJ]

1/3 of the posts say regular, 1/3 say premium, and 1/3 say it does not matter..... ????? I guess I'll keep using premium until I hear something more definitive.

 

[bobshine]

I have several chemical and petroleum enginerds in my family and they all have always said if your can is rated to run on 87 octane then you get no benefits from putting a higher octane in your car. This has also been stated in many places:

http://www.bargaineering.com/articles/why-high-octane-doesnt-matter-unless-it-does.html

http://money.msn.com/saving-money-tips/post.aspx?post=4993947a-4506-4620-936a-b30bf27a090f

http://ask.cars.com/2007/07/premium-gasolin.html

I am assuming that we all like and drive the Genesis because we feel that cost is not always an indicator of value. Same with gas, but some folks feel that higher octane gas is better for their car, because it costs more.
If higher costs means better, why are many of us that can afford a higher priced car not driving it instead of a Hyundai? Because we have grown up and know that price and value are not always the same thing.

Just my 2 cents worth...

 

[dlevitt]

Ordinarily, I would agree that paying for Premium was a waste of money unless your car "requires it". However, I was under the impression that the Genesis has some sort of variable timing that adjusts the engine for the different octane. I also read that the car has higher horsepower with premium, so there must be some difference.

My dilemma is to determine if, under normal driving, would premium give better fuel economy (both highway and city) or is it just a benefit if you "drove it like you stole it".

I've only had my car for about a month and I've tried a tank of both regular and premium. For the way I drive, I didn't notice any real difference in how the car drives. I also think that I get about 1mpg better on the highway at 70-75mph. If this is a realistic observation, then can I conclude that premium is more efficient than regulary?

Even if it is, I think that I will be sticking with regular. Since premium is about 10% more expensive (about 30 cents), I should go from 26 mpg to almost 29 mpg to make it worthwhile. I'm only seeing 26 to 27.

Is my logic correct or am I missing something?

 

[Jimmmmbo!]

From the horse's mouth (well, owners manual anyway) for 2012:

***************************************
3.8 engine
Your new vehicle is designed to use only
unleaded fuel having a pump octane
number ((R+M)/2) of 87 (Research
Octane Number 91) or higher.

4.6 engine
Your new vehicle is designed to use only
unleaded fuel having a pump octane
number ((R+M)/2) of 87 or higher.

For improved vehicle performance, premium
unleaded fuel with a Pump Octane
Rating of 91 (Research Octane Number
95) or higher is recommended.

Your new vehicle is designed to obtain
maximum performance with UNLEADED
FUEL, as well as minimize exhaust emissions
and spark plug fouling.
***************************************

What's probably confusing here is whether or not the paragraph on using premium is applicable to only the 4.6 or to both engines because the next paragraph is similarly presented but would obviously apply to both engines.

I've only used regular in my 3.8. Performs just fine for me. It sucks living in a state with mandated year-round E10 though.

 

[dlevitt]

My confusion is how performance is defined. If it means that the car will perform better and more efficiently, then it may make a difference. If it only means that the car will have better power and react better under aggressive driving habits, then that is a different story.

My gut feeling is that even if there is slightly better economy, it isn't worth the extra 10% cost of fuel. If I were to get 10% better mileage, then that would be different.

 

[EXBMWGUY]

using premium without corn (still available here if you look) nets about 15% better fuel economy which pays for the price premium....

Wally - I'm in Prior Lake and have been using either Shell no-corn 91 from the downtown Shakopee MN station or Fleet Farm no-corn 92 in Lakeville with similar mileage improvement. It's even helpful to go puregas every other fill-up.