Hey, I know this is a simple question, but I would really like to resolve it once and for all. I bought a used 89 IROC-Z Camaro a few years ago and I remember wondering then about whether or not I should be using regular or premium gas. I did some research and most answers led me to premium, but nothing was ever really confirmed. I know the owners manual for this vehicle has the true answer probably, but of course I don't have one and I really don't want to buy one just for that info. I have both Chilton and Haynes manuals for this car and none of them address this question (how convenient!!). With the 5.7 liter engine, I always assumed I would have to use premium gas, but I recently saw a car review on the 2002 camaro with the same exact engine and the writer stated that regular unleaded is OK for that car. I wrote to him asking him where he got the info (I assumed from the owners manual), but he never wrote back. Does anyone have an answer to this question or does anyone actually have an owners manual for the 89 IROC that maybe tells the definitive answer on this once and for all? Thanks....

 

My owners manual says premium, so that's what I've always run. I ran regular in it one time for about 3 miles when I ran out of gas. I had no knocking or anything but I ran it real easy. I saw in GM High tech performance they are running regular in a formula with the same engine as mine though.

 

The 2002 motor is altogether diferent from yours. The only thing that's the same is the displacement, and even that is only close, not identical.

This is one of the most interesting ways to dig into consumers' pockets that there is in our economy. "Premium" gas actually contains less energy (less fuel value) than "regular" gas; so you will get more power and better gas mileage IF (and it's a big "if" so watch out) the engine does not experience spark knock with the lower octane rating. If it knocks, the computer will pull out so much timing advance that you'll be far worse off.

The bottom line is, experiment. One tank of the cheaper gas won't hurt your car, so try it; and if the car runs the same, don't waste your money on the expensive stuff.

The advertising campaign to get people to step up is mostly an ego appeal with no technical facts to back it up; you'll probably see how effective the ad campaign really is, from other answers that you're likely to get when you ask this question. It's designed to get non-chemists to buy into the idea that their "performance" car (whatever that might mean to a given individual) "needs" the high $$$ stuff. It's like the beer or cola or cigarette brand loyalty thing: more than 90% of the users of those products can't tell the difference between their "favorite" brand and the ones they "can't stand" in a blind test; it's all image and perception. Oh, in case you can't tell, I'm in the mass media business.

 

93 octane from Crown...

 

I would be asking someone on the board here what is the correct fuel for you car by having them look in there owners Manuel.

If the motor is stock and it says in the owners Manuel to run 87 octane your wasting your money by using premium.

Years ago premium fuel contained higher levels of detergent which cleaned the injectors and that was the reason they recommended it over regular.

Now all fuels contain detergent blended in.

It wasn't because the car needed premium fuel.

I have included a picture of a piece of paper (not sure of picture quality) that was slipped in the 1986 Camaro's owners Manuel.

Chet

 

 

My 1987 Trans-AM manual says it needs premium gas.

 

Run the lowest octane gas you can without the engine pinging. If the engine pings, go to next grade up.

Chet, the scan of the letter from GM about using premium bring back some memories .... Back in mid-80s, detergent additives in pump gas was pretty rare as modern fuel injection was fairly new. Mobil, as I remember it, was one of the first companies to promote the fact that they had detergent in their gas to help keep fuel injectors clean.

Back then, my family had a new '85 Z with the then-new TPI motor and the injectors clogged used to clog up like crazy every few months because the gas was so dirty. Mobil gas was about the only thing you could put in it to keep it running half way normal. Can't recall what they called the grade of gas, but it wasn't cheap.

 

I'm not sure but it sounds like you are saying that premium has a lower octane level than regular. if that is what you are saying, you havent been paying much attention when you fill your car up. the higher the octane the more resistive it is to early detenation, or ping.

If you can afford it, sharky, go with the premium. if not, you probably would be fine using the the regular or "super"(octane 89 or somewhere in the area). the engines used in newer cars are manufactured to use the lower octane fuel. the cylinder walls disapate heat faster making it less likely that pinging will occur.

 

Ohhh.. so thats the noise I keep hearing..
I wondered what that was...
ok damit
now I gotta run good gas in my car?
grr
hah

 

No tamu, that's not what I said at all. "Regular" and "Premium" has nothing directly to do with how much energy there is in the fuel, or its "quality". And not to be a jerk or anything, but guessing by your userID, I've been paying attention to what happens when I fill up my tank since long before you were even a gleam in your daddy's eye.

Go hang out at your local refinery (yes, in most locations there are actually only one or 2 refineries, and ALL the gas you can buy at gas stations except for specialty stuff all comes from there) and learn what really happens. The gasoline that goes to all the stations all comes out of one huge tank, not 2 or 3 huge tanks, into the trucks. Each of the different "brands" (I use the term very loosely) has the opportunity to add their own additive package to that one base substance to create each of their "grades" of pump product. Some do, some don't. It varies by area. You'll also find out that the actual fuel formulation, as well as the additive package, varies dramatically according to the time of the year, especially in places where the temp varies widely from season to season.

The "octane rating" of the fuel is a measurement of its resistance to detonation. It does not tell you anything about "quality", energy content, or even detergent content. The more additives they add to the fuel to raise the "octane rating" or clean injectors, the less fuel there is per unit volume. In some parts of the country the "premium" is simply regular gas that has even more than usual of MTBE or similar "oxygenators" added to it; i.e. it's already deliberately "leaned out" before it goes in your tank!! That's an emissions thing: your car will emit less if the fuel contains its own oxygen, so in the vehicles that are more likely to pollute, the mfrs instructions tell you to use the fuel with extra added oxygen, and pay 15% extra for the oxygen that you could be getting for free. Kind of like buying T-bone steak at the store, that has been pressurized with red-dyed water to make it "bleed" that thin red fluid that uninformed consumers think is blood and means it's "fresh"; actually, you're just paying $10.99 a pound for water and red food coloring that covers up the real color of the meat so you can't even tell what you're really getting.

The cylinder walls have almost nothing to do with heat dissipation, it's mostly the heads. Unfortunately if heads allow heat to escape from the cylinder (which does reduce the tendency to detonate) then they are also less thermally efficient; i.e. the enrgy that comes from burning the fuel goes into the cooling system instead of turning the crankshaft. Not an ideal situation.

So, my advice remains, use the lowest "octane rating" that will work in your car without pinging. Only use the more expensive stuff if your car actually needs it to keep from pinging; otherwise you're only wasting your money. In 2 ways, no less: you'll use more gallons, and each gallon will be more costly. And at the same time, since the fuel has a lower heat content, your car won't produce as much power. Remember, this only applies as long as the engine does not ping (detonate); if it does, then you're losing power and efficiency in other ways, and you may have to spend the extra $$$ to make it stop, or alter your tune.

 

Just wana say this is a really good post. I also agree that sometimes high octane isn't always the best.

 

RB83L69 is correct.

In the mid west all fuel regardless of brand name comes from the same spigot or the local regional terminal. You can have a tanker pull up that is branded your Mama's best in the world gas and right behind it will be a BP tanker.

Quote from 86 owners manual

"However, now and then you may notice light spark knock for a short time while accelerating or driving up hills. This is no cause for concern because you get the greatest fuel economy benefit from the fuel's octane rating when there is occasional light spark knock. Using fuel with a higher octane rating than that which allows occasional spark knock is an unnecessary expense."

Chet

 

That is a nationwide system, a company just puts in "X" gallons somewhere, then they can get "X" gallons out somewhere else.
The only difference in gasoline is the additives some companies add after ge3tting the gas out of the pipeline.

 

thanks for gas refining lesson, RB83L69. im glad you gave me all that great information. unfortunately, it was a waist of my time reading it since most of it i already knew. however, it is very exciting to see how smart and wise you are with all your years. i on the other hand am just a college kid who knows nothing about the real world because i have been lock in the closest for my whole live. wake up man. being old does not make you smart. im not saying you arent smart but dont try and make me seem stupid just because im not 40 or 50 years old.

now that i got that off my chest...

im a bit confused by this statement. it almost appears that you contradict yourself. and octane rating does tell you about quality. higher octane resists detonation better. you say so yourself later in your responce.

you are right about the head dissapating alot of heat. you are also right about the cylinder walls not dissipating much heat if you are talking about older engine (maybe from the time you were young). todays block are cast to be higher quality w/ better understanding of material composition and better technology.

 

"Detonation resistance" is not the same thing as "quality". Water for instance has excellent detonation resistance, but is a very poor quality fuel for this type of engine. If you add a bunch of oxygen or various non-flammable additives to gasoline to make it more detonation-resistant, you have not improved the "quality"; you have merely covered up some other deficiency somewhere.

The newest cast-iron motor I have had the opportunity to look at wasn't very much different from any other cast-iron block I has ever seen; seems like iron is still iron after all these years.

You're right, being old does not make one smart; but being young and unwilling to see past one's own prejudices that are built up by carefully crafted advertising and other non-reality doesn't make one smart either. I don't claim to be smarter than a younger person, or really smart at all; only informed and honest and (hopefully) resistant to the oil companies' campaigns aimed at my wallet, and ready to help others avoid getting lured into wasting their money on something they don't need for reasons they don't understand. I don't want to make anyone look stupid; just like at work, I work hard and get stuff done, but it's not because I want to make lazy people look lazy or ineffective people look useless. I'm terribly sorry if it turns out that way but I'm not going to stop just for them.

 

ok, you have crossed the line. i can put up with most everything you have said up to this point, but not this. you are now accusing me of this bogus claim because of my age. how dare you go to such lengths. it is uncalled for. i have no prejudice and i CAN fabricate my own oppinions about advertisements. you also imply that i am not informed or honest. you do not know me and you need to come back to reality. others have opinions and just like me, you may be wrong.

oh yeah, almost forgot...

im glad you are able to visially distuinguish the difference in chemical compositions of materials. you should get a job working for the govt. since you are one of just a handful of ppl in the world who is able to do that. the blocks may look the same but be different in composition. a certain illegal drug looks very similar to sugar, does that mean that you should put it in your tea? also iron may be still iron, but it may be manufactured to be more dense. for instance, pencil lead and diamonds are made from the same minerals. and iron is not aluminum either. i did not specify what materials are used for the blocks.

also, your point about the water being resistant to detonation is mute. it has not real bearing to the thread. vasoline is a pretty good lubricant, does that mean you should use it in place of engine oil. of course not, stay on the topic.

 

tamu130 doesn't like old people tiring to explain something to him.

Chet

 

i dont have a problem with ANYONE trying to explain something to me. i have a problem with being discriminated against because of my age. we were having a reasonable debate on a subject and RB83L69 try to make his case seem more reasonable by bringing my age into the discussion.

 

i think that gives me every right to defend myself.

 

tamu130,

We can't help it that we are old and have more gas anymore than you can help that you are young and have less gas I would assume unless your a big bean eater.

Chet

 

beans are good for me.

and if its any of your business, i have plenty of gas to go around

 

LOL, well at least we agree beans are good and that they produce enough gas to go around.

Chet

 

Wow. I'm honored. What a fountain of information and wisdom.

I fell the need for some more hot air. Pass the beans please....:sillylol:

 

 

im not sure if you are insulting me or using me to humor others.

should i laugh or cuss?

hahaha........F*CK

 

i think that covers both

 

I use 87 almost all of the time, have for years. Like said above, fuel all comes from the same place. I used to do field surveys at various oil well and processing plants, and its all dumped in the same tank, then split and mixed into different additive packages and whatnot and sent on its way to the gas station. Water tends to find its way in there too at times... a certain amount of water can be added and have little effect on your car, but puts money in the gas station owner's pocket.

Didnt specify what materials were used for the blocks eh? Why dont you, and be specific about it.

 

Thanks to everyone for all the comments and input. It looks like it will have to just come down to testing the 87 octane to see if I get any pinging. There was one thing that "RB83L69" mentioned about the computer retarding the timing if there is pinging that I wanted to get some further clarification on. I have heard of this before but cannot actually picture what would be happening there. If the computer were to do this, what symptoms would I expect to see (beyond hesitation problems I suppose)? I assume this would create an obvious driveability problem and then I would know to use the higher octane, right?

 

we all know that blocks today are almost all made of mostly iron or mostly aluminum. my point is that the other materials involved in the casting procedure are in different quantities than have been in the past. its like glass. the glass used in most instances is relatively brittle. but if you substitute one of the molecule for a stronger one, you will still have glass but one that can sustain alot more bashing.

just like any of you, i dont know the other materials used in the blocks of engines.

 

Wow, could I explain it any better than RB? most definately not. Along with age comes wisdom, so he must be one old fu(ker.


Try puttin some CAM2 in you 9:1 compression motor, I mean you want premium for the higher octane, heck hard to beat pulling up to Mobil and gettin some $5 a gallon CAM 2, your car I bet will run worse.

 

Speak for yourself, but I figured you didnt know anything about the alloys. Aluminum blocks are running cast iron or steel sleeves that are either cast or pressed into the blocks, so the heat transfer from cylinder wall to coolant hasnt changed very much. Chamber, piston, and port designs have, and thats where 99% of the difference in resistance to detonation is along with better fuel and timing accuracy from better programming.

 

I always run premium in my car.