gas

[Warbeaver]

question regarding gas types. If you run regular and you want to switch to premium is there something special you have to do to switch it over?

also, if you make the switch to premium, are you able to switch back to regular?

[Nighthawk243]

In order to get the best use out of the particular gas type you choose, you should have the computer retuned for either regular or premium gas.

[Warbeaver]

i have no idea how or where to get a car computer tuned

[Nighthawk243]

mpracing does them for the Grand Ams.

[TA^Guy]

http://www.gaownersclub.com/forum/showthread.php?t=80748&highlight=Octane

[Matt95GT]

No gain or point in running premium unless your PCM has been retuned (timing advance, etc) for it.

Well, 2 exceptions for GA's... the 2.3 HO (factory tuned for 91 oct) or the 2.0 Turbo. Otherwise, running 87 is just fine.

[02blackgt]

No gain or point in running premium unless your PCM has been retuned (timing advance, etc) for it.

Well, 2 exceptions for GA's... the 2.3 HO (factory tuned for 91 oct) or the 2.0 Turbo. Otherwise, running 87 is just fine.

Recently gas went up in my province but when i went to the gas station they were out of regular 87 octane but they were selling premium at the same price as regular. So i put in the premium but im not sure if its good for my engine. Is it bad to run premium when you've been using regular since you've had the car?

[tenspeed]

Is it bad to run premium when you've been using regular since you've had the car?

It won't hurt anything but your wallet. See if you get better MPG's with the premium gas.

[02blackgt]

It won't hurt anything but your wallet. See if you get better MPG's with the premium gas.

lol thanks alot man will do.

[jackpot]

iv actually noticed a loss in power when using 91 octane, well I really noticed when i used this 93 octane once lol, wow what a waste of money, 87 all the way, seems to like 89, little less knock but yeeesh I see no reason not to use the cheap stuff, as long as its top tier

[tenspeed]

Some cars get better MPG's with the better gas. We had a van that liked the mid range gas. It was the cheapest cost per mile.

[whatever]

Save your money. I get the least expensive fuel they have. Around here it's 15 percent ethanol and that's our mid grade{89 octane}. Of course that hurts mileage a bit but that's what I always use and have never had a problem. My 2 cents.

Mark.

[Matt95GT]

Recently gas went up in my province but when i went to the gas station they were out of regular 87 octane but they were selling premium at the same price as regular. So i put in the premium but im not sure if its good for my engine. Is it bad to run premium when you've been using regular since you've had the car?

It will be fine.

See if you get better MPG's with the premium gas.

No, technically premium gas is more "watered down" with additives. There is actually more potential energy stored in regular. Regardless, use what your engine is tuned for... and for most that's regular.

[MagusXIII]

No, technically premium gas is more "watered down" with additives. There is actually more potential energy stored in regular. Regardless, use what your engine is tuned for... and for most that's regular.
Matt, I do have to disagree that regular has more potential energy stored than regular. If that were true, then how come running regular in, say, a Northstar gets a DECREASE in total power? And why does Porsche even say you can run regular albeit with a drop in power output?

All grades of fuel have nearly the same energy output per gallon, around 111,000btu if I remember. But premium does have a bit higher of a heating value. Problem is, it is difficult to detect in normal vehicles as there are other variables.

Also, I do not think resistance to ignition is always a case of lower energy. Take diesel for example. It has a far higher resistance to ignition than gasoline, but it has a BTU content around 130,000 per gallon.

[Nighthawk243]

Matt, I do have to disagree that regular has more potential energy stored than regular. If that were true, then how come running regular in, say, a Northstar gets a DECREASE in total power? And why does Porsche even say you can run regular albeit with a drop in power output?

All grades of fuel have nearly the same energy output per gallon, around 111,000btu if I remember. But premium does have a bit higher of a heating value. Problem is, it is difficult to detect in normal vehicles as there are other variables.

Also, I do not think resistance to ignition is always a case of lower energy. Take diesel for example. It has a far higher resistance to ignition than gasoline, but it has a BTU content around 130,000 per gallon.


The reason for the reduced power is that the PCM has to dial back the timing in order to keep the engine from having pre-detonation problems. The engines that are designed to run premium have their timing advanced for the extra power. The LE5 in the 05-08 Delta bodies (Before LAP replaced it for the 09 M/Y) have advanced timing for running 91/93, but regular timing for 87.

[RocketFast321]

yea getting back on topic, my car seems to gets the best mpg on 89.

[tenspeed]

Some cars get better MPG's with the better gas. We had a van that liked the mid range gas. It was the cheapest cost per mile.

yea getting back on topic, my car seems to gets the best mpg on 89.

That's the bottom line. If your car gets more MPG's on midrange gas, use it. If your MPG's remain the same, it's a waste of money.

You have to keep track of grade, gallons and miles at each fill up.

[Matt95GT]

Matt, I do have to disagree that regular has more potential energy stored than regular. If that were true, then how come running regular in, say, a Northstar gets a DECREASE in total power? And why does Porsche even say you can run regular albeit with a drop in power output?

All grades of fuel have nearly the same energy output per gallon, around 111,000btu if I remember. But premium does have a bit higher of a heating value. Problem is, it is difficult to detect in normal vehicles as there are other variables.

Also, I do not think resistance to ignition is always a case of lower energy. Take diesel for example. It has a far higher resistance to ignition than gasoline, but it has a BTU content around 130,000 per gallon.

For the sake of this discussion (not very detailed... more layman) I wasn't going into that detail. But yeah... if you're seeing lots of knock retard, you aren't making all the power it could. Chances are that if you're getting knock, your driving habits (high or full throttle) wouldn't favor good fuel economy anyway.

[gt00]

http://www.redorbit.com/news/science/1301690/premium_gasoline_not_best_choice_for_every_car/index.html

[ssracer]

Higher grade gas is harder to detonate/ignight. That's why high compression and boosted engines have to run it. It keeps them from blowing up. Also why if your car has always run low grade but starts to develop a knock, moving up a grade can sometimes make the knock go away.