I've always heard that you should use the lowest octane you can get away with as long as there's no knocking coming from the engine. With that in mind I've burned a couple of tanks of regular in the Eclipse and got great mileage and the performance seemed the same as with premium. In fact, I've gotten better mileage with regular than with the hi priced juice.

What's your opinion on this?

unless you have a turbo, regular gasoline is fine. with the turbo, you want a more precise burn of your fuel. that's when the higher grades come into play.

what model eclipse do you have?

my previous car was a civic and now is an 04 GS Spyder; I've always used premium on these; I have found that the engine runs smoother and better and gets better gas mileage with the high test. when I got my GS used, it had some hesitation, but I started using the 93 and it went away....remember, you get what you pay for... :crying:

2006 GT

so let me ask you this....how much are you saving per fill up by putting in the lowest octane you can buy?

now compare that with the chances of damage to the engine.

not saying that it WILL mess up the engine, but there is a chance. and thats not a chance i would be willing to take to save $2.50 a fill up

when you open up the gas cap cover on my o6 gt it says premium fuel only.

then you should use premium. i use premium.

being that i've worked on cars for 10years plus, their is no substantial evidence that 87oct is better or worse then 91oct.
The only difference is, the additives that each gas company puts in it.
anyone that tells you other wise...well (don't want to be an ****) isn't that wise.

some 3G GT eclipses will produce knock when using 87 octane. its been heard.

in the specs in my owners manual it states the compression ratio on the v6 is 10.5 to 1 you have to run premium with that compression .

jesus....i didnt know they put it that high

10.5:1 is one **** of a high compression. I've always found it okay to put the cheap gas in and add the STP fuel cleaner/octane booster. I've also found it helps with the ping/knock.
It's cheaper too

here is some interesting read: these are the gas stations with the most detergent additives. You will be surprised.

TOP TIER Detergent Gasoline Retailers

Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline.

In addition, all gasoline outlets carrying the brand of the approved retailer must meet the TOP TIER standards.

Additional gasoline retailers are added to the TOP TIER list as they meet the standards. The retailers known to be on the TOP TIER list are shown below.

TOP TIER Gasoline Retailers:

QuikTrip
Chevron
Conoco
Phillips
76
Shell
Entec Stations
MFA Oil Company

heres more info,

Important News!

Automakers, oil industry in fuel fight

Car companies want more gas additives

By STEVE EVERLY
The Kansas City Star

“Frankly, we didn't want too much input.”


Andrew Buczynsky of GM, about the new fuel standards

Some members of Big Auto and Big Oil are at loggerheads over the quality of gasoline pumped into automobiles in this country.
A consortium of major automakers, citing persistent repair problems and troubling product tests, recently concluded that the quality of U.S. gasoline varies widely and often doesn't burn clean enough to keep engines running smoothly.
And now, in a move that is roiling much of the oil industry, General Motors, Honda, Toyota and BMW have banded together to push a new industry fuel standard. If that standard is adopted, it will increase levels of gasoline additives that prevent deposits on intake valves and fuel injectors that foul engines and affect performance, emissions and fuel economy.
The new class of fuel, dubbed “Top Tier Detergent Gasoline,” is a voluntary standard that exceeds the current standard set by the Environmental Protection Agency. But gas marketers, under pressure from automakers, may find it hard to ignore, since it could put them at a competitive disadvantage.
Gasoline sold by QuikTrip — the area's biggest fuel marketer — already meets the Top Tier criteria. ChevronTexaco, which has no retail presence in the area, also has adopted the standard. Other companies, including Shell Oil, have plans to meet the new standard.
The push comes as the automakers say they are seeing persistent problems such as clogged fuel injectors and as they begin to introduce a new generation of vehicles engineered to meet tougher environmental standards. Those new vehicles especially will need fuel with more additives.
The automakers are buttressing their case with an industry analysis that tested fuel samples taken from cities across the country — including Kansas City. It shows detergent levels in gasoline dropping nearly 50 percent since 1996.
“We've just felt for a long time that gasoline detergency was not at a proper level,” said Andrew Buczynsky, a GM fuel engineer.
The American Petroleum Institute, an association that represents the oil industry, said it was surprised and disappointed by the automakers' decision to push Top Tier without seeking the advice of oil companies. The association has sent a letter to the automakers seeking the data used to back their allegations and offering to conduct additional gasoline tests.
“At this point, we're waiting for a response,” said Ed Murphy, downstream manager for the American Petroleum Institute.
Top Tier is intended to give motorists greater comfort that the fuel they buy has sufficient cleaning ability. Experts say the cost of adding the needed detergents is a fraction of a cent per gallon.
The controversy over the quality of gasoline challenges the widely held belief that all gasoline is about the same.
The auto industry analysis reveals that different brands have different detergent levels. And while all gasoline is thought to at least meet the EPA's minimum standard for detergents, the automakers say that level is often insufficient to keep engines clean.
Although the cost of introducing Top Tier gasoline would be minimal for consumers, it could threaten how some oil companies market premium fuel, which costs about 20 cents more per gallon than regular gas.
Premium accounts for about 15 percent of gasoline sales, but experts estimate that demand for premium would fall to about 5 percent if only cars that needed the extra octane used premium.
Some oil companies have sought to increase sales of premium by touting that it contains a higher level of detergents. But Top Tier will blur that advantage, since all grades, including regular, will have to meet the new standard if a marketer wants to participate in the program.
So far, Top Tier gas has received scant attention. But that is expected to change as it is included in gasoline marketing.
Automakers plan to publicize a list of gas companies offering the fuel and are developing a Top Tier logo for gas pumps. They have created a Web site at www.toptiergas. com.
Groups such as the AAA are beginning to hear about the new fuel standard. The automobile association is currently considering whether to support the Top Tier program.
“We have the same basic concerns that the automakers have,” said Michael Hecht, manager of technical services for AAA Auto Club of Missouri. “We support it.”

Questions about fuel quality once seemed settled.

In the 1980s, additives became an issue when fuel injection became popular in new cars and trucks. The injectors often became clogged, and the problem was traced to gasoline with insufficient detergent additives.
Automakers began to publish “good gas” lists. The lists wer e eventually dropped at the urging of some gas marketers, but by then the problem had eased.
Still, some gas companies weren't using detergents and, in a move supported by the auto industry, federal regulators mandated specific levels of the additives. The EPA finalized the regulation in 1997.
But something happened after the new regulation took effect: The amount of detergents in the nation's gas supply dropped sharply.
The Alliance for Automobile Manufacturers twice a year takes gasoline samples in 26 U.S. cities — including Kansas City. One of the tests is for “unwashed gum,” which is an indicator of the amount of detergents in gasoline.
In the winter following the EPA standard going into effect, according to AAM tests, unwashed gum levels in regular gas dropped more than 20 percent. By 2002, gum levels had declined about 50 percent. Although recent tests show slightly higher levels, they are still low.
Joe Colucci, a retired director of research and development at GM who now operates Automotive Fuels Consulting, said reducing detergent additives to the EPA regulation level was seen by some companies as a way to reduce costs. Although detergents cost only a fraction of a cent per gallon, it adds up to an enormous sum because of the huge volume of gas sold.
“They would say to themselves, ‘We'll meet the letter of the law,' and that's what has happened with much of the gasoline,” Colucci said.
By 2002, the automakers say repair records suggested that the EPA standard for detergents wasn't high enough. They approached the EPA about increasing gasoline detergents, but say they were rebuffed.
“We would have liked to have had some leadership from the EPA, but we just haven't been able to get that,” said John Cabaniss, a director of engineering at the International Auto Manufacturers Association.
An EPA spokesman said the agency was unaware of the industry attempt to improve the fuel standard. He said the agency's program mandates that certified detergents be used and in what amounts.

“The program is working well,” said EPA spokesman David Ryan.

But questions about the EPA standard appear to have been the focus of growing concern at industry forums, such as an vehicle emissions conference in Chattanooga, Tenn., late last year attended by oil and auto companies.
The Alliance of Automobile Manufacturers described “continuing problems from inadequate additives use” and said the EPA needs to update its regulations, according to information presented at the conference. Another speaker said he was seeing problems with fuel injector fouling even when the fuel met EPA requirements.

Some oil companies question the standard as well.

Shell Oil estimates that 60 percent of the fuel sold in the United States is at or near the “EPA minimum level of detergency” and says that has caused problems in some cars.
“We have measured significant deposit buildup in certain vehicles in as little as 5,000 miles,” Shell stated in one document.
Early this year, GM approached Honda, Toyota and BMW to join in an effort to improve gasoline detergent levels. GM believed that an organized group rather than a lone automaker would show the seriousness of the issue.
The move came at a time when automakers were beginning to produce vehicles to meet the EPA's “Tier 2” environmental standards for reduced emissions. Such vehicles need quality fuel to avoid reduced performance.
“We feel high detergency is preferable,” said Douglas McGregor, an emissions compliance engineer for BMW.
In early April, the American Petroleum Institute held a meeting in Detroit for the oil and auto industries. A week before the meeting, the association received a letter stating that the four automakers would be discussing the Top Tier program.
“We were disappointed,” said Murphy of the petroleum institute, adding that his group didn't know Top Tier was even in the works before receiving the letter.
The oil industry wasn't given an opportunity to give its advice, Murphy said, adding that a new fuel standard typically involves cooperation between the industries.
But collaboration is unlikely. The automakers say they have previously reached out to the oil industry with concerns, but nothing happened. As a result, the automakers decided to proceed unilaterally with a new fuel standard.
“Frankly, we didn't want too much input,” said Buczynsky, of GM. “Because when we have, it would always drop down to the bare minimum.”
The Top Tier standard was modeled after California's fuel quality regulations, which allow half the deposits on intake valves that the federal rules permit. Buczynsky said the amount of detergents in Top Tier-certified gasoline will be two to three times the current EPA standard.
While some brands of gas currently have more than the EPA standard, according to the auto industry's testing, there are many at the minimum level of detergent.
A gasoline marketer who wants to meet the Top Tier standard must do it for all grades — not just premium — and make it available at all stations.
While meeting the standard will require testing, automakers say they strive to minimize costs. Despite the additional detergents, the cost is expected to be a fraction of a cent per gallon.
But the Society of Independent Gas Marketers of America fears that any additional costs could prevent some members from offering the Top Tier gas.
“A fraction of a cent can be a substantial part of your profit,” said Tom Osborne, a spokesman for the group.
The independent marketers group, however, has invited a GM representative to address its members. The society's staff also has been instructed to begin helping members who want to participate in the Top Tier program. One of its major members, QuikTrip, already has qualified for the Top Tier program.
More major brands are expected to make similar announcements so competitors don't get an edge. Shell plans to have all grades of its gas certified Top Tier this summer.
For an answer to this problem see our ProTecta Fuel System Treatment by clicking Here.

To reach Steve Everly, call

(816) 234-4455 or send e-mail to severly@kcstar.com.

:thumbsup: if you can't afford the gas, you can't afford the car!!!

you should try reading the post

I'd use premium in the v6. It is a pretty high compression engine, plus with the mivec, I am sure the ignition curve is pretty advacned also, Although I do beleive there is a knock sensor that can retard it. Premium is usualy only about .10 more per galaon (at least in Michigan) so if you fill up, its like $2 more, might as well use what they recommend and spend the extra $2 :)