Klondike

Like all Vettes, mine says right on the gas cap, "Use Premium fuel". Well, the octane rating for premium varies depending where you are. I can get 93 where I live, but farther out west Texas and when I was in Colorado this summer, the highest octane premium I could find was 91. Around here the grades usually progress from reg 87, mid 89, & prem 91 to 93 depending on what brand. My point being, since the mid rating 89 is only a couple of points away from some places premium rating of 91, wouldn't the 89 be just as good for a 300 mile flat land highway criuse where you're not mashing on the throttle a lot?

1963SS

I really hate to say but it's a Vette...not a KIA. If your tank was all the way on empty you would need 20 gallons of gas. Most likely 15. Since there's only a 10 cent difference in the Mid grade vs the Premium that would be somewhere between a dollar fifty and two bucks difference........for a whole tank of gas. 400 miles or so. An extra penny or two a mile is not going to hurt most people. I know that not all Vette owners are rich but c'mon now, two bucks. I'd use what the factory recommends and not risk a performance loss.

Dig the change out from under the seats, deep in the console or where ever and go for the good stuff.

Wathen1955

In CA, all we have is 91 so that is what mine gets.

dan_t

A datalog would tell you if you are going to experience any difference. I've specifically set up my spark and fuel map with 87 so I know I'm fine wherever I go. It also means that when I want to go our for a spirited drive I can use 94 and have some extra peace of mind.

I doubt that the stock spark tables are close enough to the edge of knock that a 2-3 ron/mon changing is going effect it much.

If you ran 87 for instance and had ZERO knock then you'd have no performance increase with 100 ron/mon

markKlein

Not really true, the electronics would retard the timing before you would feel any knock (if it needed to), but you could be driving without full power available and not know it.

Having said that, I doubt if anyone cruising down the street would ever feel the difference, and it wouldn't "hurt" the engine.

Myself, I spend the extra buck a fillup, even though I probably never go crazy enough to use that last little bit of advance.

navy_vette

I used 91 when I was in Cali since that was all that was available to me. I have to do math every time I fill up out here to figure out what rating I'm actually getting.

If you have 93 available, use it. You car will be happier and run cleaner. Be careful though. It can raise your engine temps. Keep an eye on that coolant and oil temp if your running it hard.

Klondike

I have always fed the car the best stuff, but burning through a whole tank of premium while on criuse control just seems like a waste of octaine when.....yeah, your right, I'm just being a tight a$$ cheapskate.

GREGGPENN

yes and fixed.

Good is subjective for this conversation.

kenv

I have used 87 in my `87 since I`ve had it. The supercharged `90 on the other hand sees nothing but 93.

1963SS

The OP has an LT4. That has 10.8:1 compression. It's a bit more than the LT1 and a bunch more than an L98. The 87 Vette had 9.5 (?) compression and the 90 has 10.25. Both are well below the 10.8 of the LT4. Using light throttle pressure just cruising the lower octane may be OK but with that compression it's going to be very dependent on the engine temp also. I wouldn't risk it. But that's just me. Every 15 gallons is an extra $1.50. Don't buy the Cappuccino when you fill up.

QCVette

I am not sure of the LT4.

I have used 87 octane quite a bit in L98 and LT1 cars.

There is a noticable difference in performance if you use a lot of throttle so I usually use premium, but if it is for a trip and just on cruise control on the highway I have no problem using 87. It saves a little money, and yes, I know I am cheap.

JackDidley

100%. Very good explanation.

RollaMo-LT4

There have been a few times when the highest octane available was 89, and I have used it.
But I wouldn't make a habit out of it.
As 1963SS mentioned, using light throttle (basically cruising down the interstate) shouldn't give any problems for a tank if that was all you could find.

As mentioned, the OP has an LT4. The higher compression requires a higher octane than the LT1 or L98
You probably won't cause any damage running a tank of 87 or 89, as long as you didn't "get on it".

From the '96 owners manual:

H P Bushrod

RetiredSFC 97

In the Lt 4 I would use the 91 if possible.

However,

If your state uses ethanol then did you know that the 87 and 89 has the same octane? They put ethanol in the 87 to make it 89 so they just mix it all and it all comes out a minimum of 89. The laws state they have to have that minimum, i.e. 87/89. So the 87 does have the minimum but in truth has over 89.

My point is, if you are going to use 89 you might as well put 87 in it because it's the same, again if your state requires it. In Mo, they do require it.

However, I don't think they do this for 91 and above, so 91/93 is typically real 91/93 octane without ethanol. Which is much better for your car and your mileage.

So with all of this said, I did use 89 on occasion in my L98, but not often. I have also used 89 in my STS Northstar and a couple times in my LS1. But I don;t make a habit of it.

Even though I know the 87 has at least 89 octane I can't get myself to use it for whatever reason. Weird I guess.

Around here 91 is typical and only a couple places sell 93 and it costs out the gazoo, while the 91 is 30 cents more expensive than 87.

Oh yeah, there are some places that sell the 87 and 89 at the same prices here because of what I stated earlier. But others rip you with the 89 because like I said, it's the same stuff in Missouri.

So if you ever come to Mo, you know about gas now.

GREGGPENN

Where/how did you figure that out?

I believe 91 and 93 octane often -- if not usually -- contain ethanol. Websites about the few (and remaining) 100% gasoline stations support my assumption. FWIW, corn alcohol fuels have better octane than gasoline. Makes it easier to get higher octane. That's the attraction of E85 with it's much higher octane. (Assuming you want/need to convert).

RetiredSFC 97

Kansas City Star, The (MO)
April 13, 2008
Section: FRONT
Edition: 1
Page: A1

Before you buy gasoline, check out the octane ratings
STEVE EVERLY, The Kansas City Star

Consumers are getting confusing pricing signals at area gas stations, thanks to how retailers are handling a flood of ethanol-blended fuel.

Some area gas stations have started selling both regular and midgrade gasoline at the same price, saying there is no longer a difference between the fuels.

Other retailers, though, are still charging more for midgrade -- causing some consumers to spend more per gallon than they otherwise could.

Given that the average household buys about 1,200 gallons of gas annually, households that switch from midgrade to regular would save $120 or more per year at recent pricing spreads. The difference is worth millions annually for retailers in the Missouri-Kansas region.

The pricing discrepancy comes as ethanol-blended fuel roils longstanding assumptions about the octane ratings of gasoline, making it more dubious than ever to pay extra for super-unleaded or other midgrade gasoline.

E-10, a blend of 10 percent ethanol and gasoline that is widely used in this area, has boosted the octane rating of regular gasoline from a minimum of 87 to at least 89 -- the same as required for midgrade gasoline. But many area gas dealers are still charging more for "midgrade" fuel.

It's not as though the average consumer, already grappling with record-high gas prices, would know.

The majority of gas pumps in the Kansas City area still state that their regular has a minimum of 87 octane even though it's above 89. Meanwhile, midgrade is still posted at a minimum 89, suggesting there is a difference when compared with regular fuel.

Moreover, even if you're aware that E-10 has more octane, gas stations in Missouri and Kansas are not required by law to disclose that they're selling the fuel.

The main hint that something is afoot in a marketplace comes from the handful of stations that are selling regular and midgrade at the same price.

Hy-Vee's gas stations in Missouri are selling regular and midgrade at the same price. In Platte City, you can find a Casey's convenience store doing the same thing. And in outstate Missouri, chains such as MFA and Kum & Go also sell the two grades at the same price.

Officials at Platte-Clay Electric Cooperative, which has gas stations in Platte City and Kearney, said they rejected charging more for midgrade because it's the same fuel.

"We would probably make a few more dollars," said Bill Estes, manager of marketing and communications at the cooperative. "And it's not against the law. But it's not ethical -- I don't think."

In most parts of the Kansas City area, though, it still costs more to purchase midgrade gas than regular.

QuikTrip, the area's largest gas retailer, is charging 10 cents more per gallon for midgrade gas, even though its regular gas now exceeds the minimum midgrade octane level. At one Shell station last week, the cost for regular was $3.16 per gallon and its midgrade fuel was $3.28 per gallon.

Shell, in an e-mail response to questions, said it sold wholesale fuel that contained 10 percent ethanol for both its regular and midgrade fuels. The company noted that the gas meets the minimum of 87 octane for regular gas and 89 for midgrade. And the minimum octane levels are posted for all grades on fuel pumps, as required.

Shell, which has exited the retail end of the oil business, said pricing is left to the owners of the stations.

"Shell retailers are independent business people and set the prices of the fuel they sell to consumers," according to the e-mail.

For its part, QuikTrip said it was selling ethanol-blended fuel for its regular, midgrade and premium lines of gas. The company added that it was blending its regular and premium gas to make its midgrade, which gave it slightly more octane than regular and "more bang for the buck."

A gallon of E-10 regular has an octane rating of 89.6. Based on information provided by the company, QuikTrip's midgrade would have slightly higher octane of 90.3 if blended with premium. Its premium grade, meanwhile, has a minimum 91 octane rating.

Mike Thornbrugh, a spokesman for QuikTrip, said the company plans to continue charging 10 cents per gallon more for midgrade than regular. But he added that the company was mulling over providing more information about octane levels of each grade.

"It's something we'll probably take a look at," he said.

QuikTrip last week still had decals on its pumps that said its regular fuel had a minimum of 87 octane and its midgrade gas had 89 octane.

Octane ratings are used to indicate the fuel's ability to resist pings and knocks.

About 15 percent of drivers purchase midgrade or premium gasoline, according to the Energy Information Administration. But many experts question whether many of those purchases are necessary.

Jon Linkov, managing editor of autos for Consumer Reports magazine, said most cars perform fine with regular fuel and the average motorist wouldn't notice any difference between a 90.3 octane rating and one that was 89.6.

"In fact, unless you're tuning your car with a computer, with varied fuel/air mixtures -- think hard-core racing -- even a guy driving a high-performance car won't see a single benefit from going to 90.3 octane versus 89.6," he said.

Confused consumers

The situation, if nothing else, is sowing confusion for consumers who are beginning to notice.

David Peironnet of Gladstone noticed the same price for both regular and midgrade gas at a Hy-Vee station -- and noticed the pump stated that both had 89 octane. But when he later purchased gas at a competitor, those pumps said regular had 87 octane and midgrade had 89 octane at a higher price. Therefore, he assumed there was a difference.

"That is outright deception," he said.

Retailers, though, are following the rules as they are now defined.

The Federal Trade Commission, which sets the rules for the octane disclosure, requires only that the gas meet the minimum ratings posted on the pump. State inspectors check the fuel to ensure that the 87 minimum for regular is met, for instance, and aren't concerned if it's actually high enough to qualify as midgrade fuel.

"We don't have a problem with that," said Ron Hayes, a manager with Missouri's Weights and Measures Division.

But others, including ethanol proponents, find the lack of information frustrating since ethanol's richer octane content could save money for consumers who want some additional octane but don't have to pay more for it.

Gary Marshall, chief executive officer of the Missouri Corn Growers Association, said he has asked gas-retailer representatives why midgrade gas costs more than regular.

"I try to tell them it's the same product," he said.

Missouri has a mandatory E-10 law that took effect in January that requires gas stations in the state to sell ethanol-blended regular and midgrade gas unless its wholesale price becomes more expensive than traditional gas.

Two other states -- Hawaii and Minnesota -- currently have an E-10 mandate. And a third state -- Montana -- will enforce a mandate when it produces sufficient ethanol to supply the state.

Several other states have renewable-fuels standards that encourage the use of ethanol. Beginning in 2009, Kansas will give fuel retailers tax credits for selling E-10. But even now E-10 is widely, but not universally, available because of its lower wholesale price.

(Critics of ethanol-blended fuel note that its lower energy content diminishes mileage, which could offset the advantage of its lower price.)

In Kansas, a mixed bag of ethanol-blended and other gas also can lead to unusual pricing signals for consumers.

At a Hy-Vee station in Mission, for instance, E-10 midgrade was being sold next to regular gas that wasn't blended with ethanol. As a result, that station actually was offering midgrade gas that was a penny cheaper than regular.

It's unclear how many consumers elsewhere in the U.S. may be paying more for midgrade even though it often has the same octane as regular. About half of the gasoline now used in the United States contains ethanol -- mostly E-10 -- and that figure is expected to increase following approval of new federal legislation requiring more ethanol production.

Wholesalers in some areas, however, are supplied with lower octane gas that when blended with ethanol still produces regular fuel with an 87 octane rating. Hayes, of Missouri's Weights and Measures Division, said that's the case in St. Louis.

Midgrade and premium gas have long been a profitable niche in the fuel retailing business because of the larger profit margins.

In 2006, Missouri and Kansas motorists bought about 198.9 million gallons of midgrade gas, according to the EIA. Assuming those motorists shifted to regular at current prevailing pricing spreads, they could save millions of dollars a year.

In the last several months, demand for midgrade has actually climbed. But that is thought to be largely because of those consumers who are able to purchase midgrade fuel at growing numbers of stations offering midgrade for the same price as regular.

Paying extra for midgrade fuel has long been considered a questionable value even when it had higher octane than regular fuel.

Motorists in the U.S. spend millions of dollars each year on higher-octane fuels they don't need, according to the FTC. Although octane helps prevent engine pings and knocks, higher octane is only needed in a small percentage of vehicles.

Some think the higher grades are better at cleaning the engine. But the Environmental Protection Agency requires detergents in all gas. The EPA requirements have been criticized as too low, and several automakers established a new standard for all grades, including regular. Gas brands that have met those requirements can be found at toptiergas.com.

Linkov, of Consumer Reports, said automakers require premium fuel, which has a 91 octane rating, for a relatively few models that have high-compression engines. Even consumers that have vehicles that "recommend" premium can probably do without it. The grade of fuel needed for a vehicle is stated in the owner's manual.

For most cars, regular gas, even with an 87 octane rating, should do fine. All of this suggests that paying extra for midgrade, especially when it has the same octane, is a mistake.

"You can save yourself 10 cents a gallon," Linkov said.

1963SS

I called a friend of mine at the refinery lab here in Ashland, KY. We have a good sized refinery right here in town and he said that they check octanes all the time. They blend for summer, winter and in between. The 10% ethanol that they use is figured into the final calculation and although the 87 is a minimum number it usually runs with .1-.3 points of that. The 89 is the same way. Premium still uses ethanol. They have to put some retardants in it to slow down the combustion because premium burns more slowly than regular.

So, according to the article you posted there may be a difference in the way other states do business but not around here. The engineer that I talked to is in fact a close personal friend and would not tell me the company's mantra just to make me happy.

There are mistakes in the article but it's not really worth pointing them all out. Many cars today are raising compression to get higher efficiency and require a higher grade of gas. Yes, they will run on a lower grade but not to their potential. I have to run premium because of my 11:1+ compression but anyone else can run what they're comfortable ith. Personally, I buy a high performance for the performance and I'm not about to let a buck fifty a tank take away from that, no matter how slight.

As I mentioned....these are Corvette's, not KIA's.

RetiredSFC 97

It's Missouri and not every one uses the same procedures obviously

damn C4 gen is turning into C5 gen and OT. argue just to be arguing. Try to post some info for people and all they want to do is argue about it and tell me it's incorrect.

I'm outa here, see you fellas when you buy a C5.

1963SS

Oh c'mon Sarge, don't be that way. There's no need to argue. I don't. Just state the facts and watch as someone Googles frenetically trying to prove a bad point that was made in haste. Some will search for an hour to find the one post,(by anyone) that supports their conclusion rather than admit an error. Haven't you noticed that? Geesh, it's the way of the internet. Just step around those folks and revel in your ability to give positive reinforcement to someone trying to learn.