Regular vs. Premium Gasoline

[Serendipity]

Which do you fill up with? And why?

I was always under the impression that if your car requires regular and you put in premium, you are wasting your money. However, I've heard quite a few say that if your car requires premium, using regular gasoline will cost you more. Whether it is in repairs or MPG I don't know. So, is this a myth?

[BaggedLancer]

My car says premium fuel only but I use biodiesel because it's better for the environment.

[Serendipity]

Haha. I have a neighbor that insists it doesn't make a difference. Well with ordinary cars, that is...

[MacLeod]

My Dodge Ram actually said in the manual not to use anything other than 87 octane. Said it wouldnt hurt anything but there would be no benefit from it and it would be a waste of money.

With my Honda Accord, I still use 87 octane.

[obieone]

It's been my LIMITED experience, that premium provides better gas mileage.
I don't drive my P.O.V. enough to worry about it, and my co. vehicle requires reg. gas-they pay the bill, they pick the gas.

[dkg999]

I use premium in the toys (ATV's, dirt bikes, street bikes). The lower cylinder temperatures from the more even burning of the fuel reduces wear, ping, etc.

[AsSiMiLaTeD]

Someone like Jstas can explain this better, but I think it has something to do with compression ratios. basically most normal cars run just as good on regular as they do on premium. So if your car says regular, then premium is a waste

I think the QUALITY of gas matters more than the octane. I only use Chevron in ours. I had to put some Racetrack gas in once because we were too low, and I really could notice a difference in how the car ran, especially when idling.

[Face]

Which do you fill up with? And why?

I was always under the impression that if your car requires regular and you put in premium, you are wasting your money. However, I've heard quite a few say that if your car requires premium, using regular gasoline will cost you more. Whether it is in repairs or MPG I don't know. So, is this a myth?

If a car calls for premium, use premium. Otherwise you're putting your motor and wallet at risk. Plus the fact that you'll be down on some horsepower and possibly some fuel economy.

I use 93 in both of my rides since they both call for premium. One of them even gets a splash of 100 once in a while. :)

EDIT: Too much octane can actually cause your car to lose power. I'd added 111+ octane before and have run slower, but more consistent. I love that smell. :D

[Serendipity]

Well, at $3.59/gal, it's just so tempting to fill up with a lower grade.

[MacLeod]

I think the QUALITY of gas matters more than the octane.

I definitely agree. I stay away from the Racetracs and the Midnight Oils and all the other cheap-o places and stick with the name brands. I think Chevron is the best but I think that as long as you stick to the big dawgs like Shell, BP, Exxon and Chevron youll be ok.

[Face]

http://www.toptiergas.com/retailers.html

[BaggedLancer]

I suggest a can of Zylene everyone once in a while in your Maxima appadv. You can find it at home depot in the paint department.

[bobman1235]

Yup, read your manual and use what it says. An engine designed for 87 shouldn't have 93 in it, just like an engine designed for 93 shouldn't have 87 in it.

[Face]

Yup, read your manual and use what it says. An engine designed for 87 shouldn't have 93 in it

I believe years ago Saturn stated in their manuals that premium could damage their engines.

[J_Kennedy]

My car says premium fuel only but I use biodiesel because it's better for the environment.

But you're talking about diesel, that's a whole other ball game. :D From one oil burner to another!! And I wish we had biodiesel available around me!

As for premium vs regular.......ya, there's a difference. Although it gets complicated because "some" cars have enough intelligence that they will adapt to premium but advancing timing to take advantage of premium (most newer cars do, but not all, and it's not always $$ wise).

If your car says 87 octane, use a good quality 87 octane. To run premium will actually degrade performance because it's not tuned for the slower burning high octane so you'll not be burning the gas efficiently. If you compared 2 to 3 tanks you'll likely see a lower MPG running premium. But for example, at one time I had a 2000 Expedition. The ECU's were/are adaptive, so to run premium would take 2-3 tanks for it to adapt to the slower burning fuel and you would actually start feeling a little better performance, and 1 maybe 2 MPG better economy. However, if you did the math, it wasn't enough to make it worth while. It does nothing for "cleaning" motor or anything like. Cleaning the engine is the additive package only. Fuel it fuel, additives are what make Shell different from Exxon from Jiffy Mart etc.

If your car is supposed to run 92+ octane, run 92+ octane. You can do damage by not, because the motor is tuned to burn the slower burning gas and the fast burning lower octane can cause pre-ignition which is when the quicker burning lower octane fuel ignites before it should.

Some cars you just won't see a difference but it's usually not doing it any good or even doing it harm to run a fuel it's not designed for. Some cars again, have engine control that's smart enough to adapt and at least, keep harm from happening.

Most higher end cars will require high octane because the intention is to get every bit of performance they can out of it, knowing the $0.10 to $0.20 per gallon premium for the fuel isn't an issue for the buyer.

Like I said, diesel is a whole other ballgame, but now were talking compression ignition vs spark ignition for gassers.

[J_Kennedy]

I believe years ago Saturn stated in their manuals that premium could damage their engines.

Very well could be. It would cause detonation which would be caused by the slower burning (I'm saying slower burning, and that's not entirely accurate, but sufficient for the example) fuel which could cause what is basically a second ignition of the gas that's left in the chamber after the first because the fuel ignited late in the cycle; both within one combustion cycle. If that makes sense. :D

[Refefer]

You can go up the chain, 87 octane to premium, but you'll screw your car/truck/vehicle to holy hell if you do it the other direction. It's been my experience that it's a waste to use anything except what the manufacturer tags the car for.

[J_Kennedy]

I suggest a can of Zylene everyone once in a while in your Maxima appadv. You can find it at home depot in the paint department.

Uh, ya...... I would NOT recommend doing that to anyone that doesn't know their motor their fuel and exactly what they are doing. Not saying I haven't, but the best application is for example, a friend that had a street/strip Camero back in the 80's, I'd get him a gallon every now and then, but he built the motor, knew what he was doing when mixing, and would make the changes necessary to take advantage without tearing something up. With mine that was mild street, it just made it run like it was about to jump out from under the hood! :D It would literally sound like I cranked the timing up about 10-15 degrees. You could feel what felt like a double combustion on every cycle, adn this was back when emissions equipment was a smog pump that was disconnected. :D

[Face]

I believe Zylene and Toluene are around 113 octane. If you run either straight, you need to add some Marvel Mystery Oil.

I used both in my Buick years ago. They leave odd engine deposits.

[jcaut]

Some cars- those with high compression ratios or forced induction: those that run high cylinder pressures- need the additional octane to avoid preignition and possible engine damage. If your vehicle doesn't call for premium then it's just a waste of money. I doubt you'd hurt anything except possibly fuel economy, but that's important. Most newer vehicles that "require" premium can more-or-less adapt to regular via the computer adjusting the timing so that pinging isn't excessive. That'll cost you power and some fuel economy. It's best to follow whatever the owners manual says.

My cars all need premium and that's what I use. I'm in a rural area and as gas prices go up and up and up, I'm afraid that people will quit buying premium. More than a couple of the stations here have actually quit carrying it because (they say) they don't move enough of it to keep it fresh. I hate to have to start blending my own....

[Rivrrat]

My 05 F-150 manual says regular, so I run regular.

[shadowofnight]

I made the choice ( For more horsepower of course ) to go with a map changeable system ( I use the cruise control to cycle between maps ) and I get to pick if I want to use lower octane fuel and a map designed for maximum fuel mileage or higher octane fuel and a map designed for maximum horsepower ( You just have to make sure your tank is filled with 92/93 octane to use the highest performing maps )

You can tell the difference immediately in the ass dyno ...real dyno...and on the laptop screen if I have it connected (Usually laptop only at the track).

It's called the OSIRIS system by UpRev http://www.uprev.com/products/osiris_NI.html

I use the maximum map all of the time on the street or the track and just pay a little more for the higher octane fuel......

[J_Kennedy]

Some cars- those with high compression ratios or forced induction: those that run high cylinder pressures- need the additional octane to avoid preignition and possible engine damage. If your vehicle doesn't call for premium then it's just a waste of money. I doubt you'd hurt anything except possibly fuel economy, but that's important. Most newer vehicles that "require" premium can more-or-less adapt to regular via the computer adjusting the timing so that pinging isn't excessive. That'll cost you power and some fuel economy. It's best to follow whatever the owners manual says.

My cars all need premium and that's what I use. I'm in a rural area and as gas prices go up and up and up, I'm afraid that people will quit buying premium. More than a couple of the stations here have actually quit carrying it because (they say) they don't move enough of it to keep it fresh. I hate to have to start blending my own....

Now see, you said it all pretty much in a nutshell, compared to my 3 chapter novel!! :D

Our new car (picked it up Friday afternoon) also requires premium, which we haven't had in a while. My wife's well aware as she's driven 14 others of this same make, all of which required premium, so she'll take care of it. My boat as well, requires premium which on some lakes is hard to find and when I have found it, sometimes I don't trust it, so I fill up on the street to make sure. I certainly can't afford to toast that much motor because of bad or wrong octane fuel.

[Ron-P]

91 and up only. My manual says to use nothing less.

Well, at $3.59/gal, it's just so tempting to fill up with a lower grade.

It's only, what, on average maybe .15 more per gallon. On a 20 gallon fill-up that's $3.00, hardly a wallat breaker everytime you fill up. Less then the cost of a fancy cup of Starbucks.

[Mike Kozak]

I have a 92 cadillac with only 55000 miles on it. If I do not put premium in it, I hear spark knocking.

[tonyb]

91 and up only. My manual says to use nothing less.


It's only, what, on average maybe .15 more per gallon. On a 20 gallon fill-up that's $3.00, hardly a wallat breaker everytime you fill up. Less then the cost of a fancy cup of Starbucks.

Agreed. Just use what the car company says to.Not hard.Premium for me.
Could never understand why people bitch about a .10-.20 difference in gas prices.I probably give more to bums on the street than that.

[J_Kennedy]

Diesel has been bouncing $0.10 to $0.30 a gallon which makes no sense. But I'll watch for a big difference if I'm needing to fill up. I've got a 45 gallon tank so $0.20 a gallon is more than a buck or 2. And there can be that much of a difference in north Texas.

It's crazy. Diesel was $1.20 - $1.30 a gallon 4 years ago when I got it.

[Serendipity]

Agreed. Just use what the car company says to.Not hard.Premium for me.
Could never understand why people bitch about a .10-.20 difference in gas prices.I probably give more to bums on the street than that.

What if your car requires 91 octane, and the only available choices are 87, 89, and 93?

Would it be safe to use 89 octane in place of the 91?

[Face]

No, you would go up.

[schwarcw]

I use premium in my old Buick with a 3.8 V6. It just runs better with premium gas. Premium doesn't just mean Octane rating. It's using refined better and burns cleaner. It will also be better to keep your fuel injectors clean.

In my wife's newer car, 87 is just fine. No knocks and it seems to run just as well with 87 vs 93. I still use premium gas since it burns cleaner, keeping the internal engine components cleaner.