USAToday: No Premium!

[Jesda]

Why use premium gas when regular will do?By James R. Healey, USA TODAY

Marti Mayne once fueled her low-octane Subaru with high-octane gas. Not now. Premium-gas prices "went sky high, and now I just use low grade" to motor around Yarmouth, Maine, where she runs a marketing business.----------Cost differences between regular and premium is as plain as, well, the sign at the station, like this one in Chicago. ----------When prices dropped earlier this year, she stuck with cheaper fuel because "I don't think that my car runs any differently on high, medium or lower grade."

She's right. Engines designed for regular fuel don't improve on premium and sometimes run worse. And today's engines designed for premium run fine on regular, too, their makers say, though power declines slightly. (Background: About Octane ratings)

But premium lovers are passionate. "I would simply curtail driving rather than switch grades," says Bill Teater of Mount Vernon, Ohio, who puts high-test in both his Cadillacs, though only one recommends it. He's sure both the DeVille and the Escalade run rough and lack pep on regular.

Prejudice and preference aside, engineers, scientists and the federal government say there's little need for premium.

When fuel's cheap, motorists are willing to pay 20 cents or so more for premium. But as gas prices sneak back up, the mental wrangle begins anew over whether it's OK to burn cheaper, regular-grade gas.-----------> AS PRICES RISE, CONSUMERSSHUN PREMIUM GAS Average price of a gallon of premium gasoline:1993 $1.301999 $1.362002 $1.5820031 $1.80Premium gas share of all gas sold:1993 19.9%1999 16.8%2002 13.5%2003 12.1%Sources: Energy Information Administration, American Petroleum Institute----------The answer almost always is yes.

"I personally use regular even though my owner's manual says you'll get better performance with premium," says Lewis Gibbs, consulting engineer and 45-year veteran at Chevron oil company. He's chairman of Technical Committee 7 on Fuels, part of the Society of Automotive Engineers (SAE) Fuels & Lubricants Council. Gibbs knows gas.

"My wife runs midgrade (89 octane) in her car, and it's a turbocharged engine" meant for 91-octane premium, he says.

Premium — gasoline having an octane rating 91 or higher — is just 12.1% of sales this year, down from 13.5% in 2002, when it was 22 cents a gallon cheaper, and well below the modern high of 20.3% in 1994, when it was 49 cents cheaper, according to industry and government data. Despite the allure of premium, once they abandon it, most motorists don't come back, the data suggest.

For every dime increase in the price, sales of premium gas drop 1%, Bob Johnson, general manager of gasoline and environmental services for the 7-Eleven chain, figures, based on data back to 1998.

The main advantage of premium-grade gas is that it allows automakers to advertise a few more horsepower by designing and tuning engines to take advantage of premium's anti-knock properties. But auto engineers generally agree that if you use regular in a premium engine, the power loss is so slight, most drivers can't tell.

"I go back and forth, and I'm hard-pressed to notice" whether there's regular or premium in the tank, says Jeff Jetter, principal chemist at Honda Research and Development Americas. He drives an Acura designed for premium.

Import brands, especially, use premium fuel to distinguish their upmarket models. Most Toyotas, for instance, are designed to run on regular or midgrade, while the automaker's Lexus luxury brand prefers premium. Same with Honda and its Acura luxury line.

"Generally, the more expensive the vehicle, the higher the expectation for performance and the more the customer is willing to pay for fuel," says Pete Haidos, head of product planning for Nissan in the USA.

Actually, the price debate is nearly worthless. At 20 cents more for premium, pumping 20 gallons of it instead of regular would cost $4 more. Annually, that's a difference of $171 for a vehicle that averages 14 miles per gallon — as some big sport-utility vehicles do — and is driven 12,000 miles a year.

Gasoline retailers and refiners like high-test because it's more profitable than regular-grade gas is. The retailer paid about 8 cents more for the premium you pay 20 cents more for — though that margin can swing wildly. Refiners make a few cents a gallon more on premium than on regular when they sell to wholesale distributors.

As long as it's clean

Profit is meaningless to the modern engine, which, regardless of what's specified in the owner's manual, hardly cares what you use — as long as it's clean.

Today's engines use highly evolved versions of a device called a knock sensor to adjust settings automatically for low-octane gas. And more engine control computers have adequate memory to allow separate sets of instructions for various octanes. The engine control computers keep pushing to maximize performance on whatever grade of fuel is used.

Extreme pressure inside the cylinders causes knock, which is the sound of the pistons literally rattling inside the cylinders. Too much too long can damage the engine. A little now and then won't.

The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors.

Burning regular when the owner's manual specifies premium won't void the warranty, nor damage the engine, even the most finicky automakers say. "You're giving up perhaps just a little bit of performance that a customer wouldn't really even notice, it's so slight," says Furey.

Automakers say they don't test premium engines on regular to check the difference, but some auto engineers estimate that power declines roughly 5%.

"We can't guarantee the vehicle will perform as specified if other than premium fuel is used," says Mercedes-Benz spokeswoman Michelle Murad. All U.S. Mercedes engines specify premium.

All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches.

Premium, in fact, sometimes is worse fuel than regular. It resists knock because it's harder to ignite than lower-octane fuels. As a result, some engines won't start as quickly or run as smoothly on premium, notes Gibbs, the SAE fuel expert.

High-test does have a potential fuel economy benefit. It is slightly denser than lower-octane gas, meaning there's a little more energy in a gallon. But the small difference is hard to measure in real-world use, and that same density can contribute to undesirable buildup of waste products inside the engine.

No data show that engines designed strictly for regular run better or longer on premium.

The Federal Trade Commission, in a consumer notice, emphasizes: "(I)n most cases, using a higher-octane gasoline than your owner's manual recommends offers absolutely no benefit. It won't make your car perform better, go faster, get better mileage or run cleaner."

There is "no way of taking advantage of premium in a regular-grade car," says Furey.

"There is no gain. You're wasting money," insists Jim Blenkarn, in charge of powertrains at Nissan in the USA.

"No customer should ever be deluded into thinking there's any value in buying a higher grade of octane than we specify," says Toyota's Paul Williamsen, technical expert and trainer.

But premium retains a mystique.

Even Mayne, the sensible Subaru owner who has switched to regular, says she'll buy premium when her neighborhood station has a special price. "It's my perception that I might get better gas mileage or that it might be better for my engine," she says.

"I would stop driving rather than use a lower grade of gasoline," says Andrew Martschenko of Boston, who drives a 2003 Nissan Maxima. Nissan says premium is "recommended" for that engine — automaker code for regular is OK, but you'll only get the advertised power on premium.

If the price difference between regular and premium grew to $1, Martschenko says, "Then I might consider trading down" to regular.

Guilt plays a part

Some people feel almost guilty, as if they are abusing their cars, when they don't burn premium, says gasoline retailer Jay Ricker, president of Ricker Oil of Anderson, Ind., which operates 28 stations. "They go all the way down to 87 (octane), but maybe every fourth tank they put in the good stuff."

Sam Turner has seen the appeal, too. He's president of Favorite Markets of Dalton, Ga., which operates 139 outlets in three states.

He recalls visiting one of his stations during a price war with a nearby station, which had cut the price of premium to just 4 cents more than regular, instead of the usual 20-cent difference.

"A customer was waiting and asked me if I was going to match the guy across the street. I said, 'Yeah,' and he said, 'Good. For 4 cents, I'm gonna buy super.' "

[elwesso]

Good reading... Just more hype IMO

Im gonna keep putting the good stuff in my Q personally.....

[Need4Speed]

Yeah well add in the cost of 2 knock sensors at $100 apiece and then tell me how cheap it is to run regular. There is no way in HE_LL that I'm gonna run regular with the upcoming summer temps....can you say KNOCK.

Andy

[elwesso]

I dont think running regular has anyhting to do with wearing on the KS sooner... Its an electronic device, and its gonna fail when it fails, IMO... its always working, just wether its chanign things or not.....

[Need4Speed]

From what I understand the knock sensors kick in when you get knock from high air temps and low grade fuel. The more the knock sensors are used the the shorter the life.

I can't even run regular unleded in my AMC (Jeep) 360 in the summer as it knocks so bad....and the compression ration in that motor is way less than the Q's 10.2:1. The AMC's problem is that it was designed to run on regular not unleded.

Andy

[elwesso]

The KS are constantly active, as they merely listen to whats happening, and when they "hear" knock, they tell the ECU to retard timing...

[Dust N Bones]

"There is no gain. You're wasting money," insists Jim Blenkarn, in charge of powertrains at Nissan in the USA.

I find that statement the most interesting.

[elwesso]

You have to ask yourself, if they think its a waste, why do they all seem to recommend premium?????

[maxnix]

The car runs hotter with retarded timing, which will happen with too low an octane fuel, and will therefore affect KS durability, as well as other components (catalysts, O2 sensors, etc.).

[96QQ45]

Some folks will try to run regular or mid-grade in the Q just like they'll spend $50,000 on one and opt out of the CD changer to save money and go with casette only. Doh!

[Q45tech]

The KS are pure mechanical piezo electric microphones. They send a voltage via their harness to ecu.......the ecu measures the voltage build up on a constantly discharging capacitor.......signals per second and strength of signals: 4 fires per rpm so 2000/60= 33.3 x 4= 133.3 possible knocks per second.

Much more likely to have knock with sudden depression of throttle at 2,000 rpm.

Instead of reading soda pop newspapers try some meat.

http://delphi.com/pdf/e/int_flat_knock. ... da...s.htm

http://216.239.51.104/search?q...hl=en

http://www.dima.unipa.it/~pipi...m.pdf

http://www.thielert.com/en/aut...g.pdf

[Jesda]

I seriously doubt, when Jim Blenkarn made his statement, that they asked him about G50s.

[AZ94Q]

Exactly, Jesda..

On an american car, this may hold some merit. Since the domestic automobile manufacturors know how crappy US gas is anyway, there may be no need for the premium on most vehicles..

Hell Cadillac says plainly no premium needed for the northstar..

On a German or Japanese car? I don think so.. Since there gas is way different then ours, I wouldn't go using cheap gas, espically if it says not to.

[AlabamaDan]

In my 98 QX4 I run regular unleaded 87 octane, just as recommended in the manual. In the Q45, I run premium for the same reason. I figure if Infiniti is honest enough to say 87 octane is ok for the QX4 then they must mean it for the Q45.

BTW, ever notice that all that gas comes out of the same tanker truck?:pface

[SmithSR]

knock, which is the sound of the pistons literally rattling inside the cylinders. Too much too long can damage the engine. A little now and then won't.

Run that by me again...?

[AZ94Q]

I wish we could just agree to dump these $hitty fuel additives. They are driving gas prices through the roof. I know it isn't the only cause of rising crude, but if you look at locations in the south, and other places that use real gas without additives, they are usually 20 cents cheaper..

It's ridiculous Phoenix doesn't use the same gas that Tucson uses, or that LA uses, or that houston uses etc etc..

All that extra refining and tight capacity is killing us at the pump..

I paid $2.35 a gallon today near downtown phoenix... That was inflated, granted, but you will be hardpressed to find gas under $2.20 right now in maricopa... maybe $2.15 at the cheapest..

Anything over 2 is brutal.

[AZhitman]

I run premium AND an octane booster.

If you can afford a Q, you can afford the gas.

If you can't, buy a Civic, and sell the Q to a more deserving owner.

[HeavyDuty]

knock, which is the sound of the pistons literally rattling inside the cylinders. Too much too long can damage the engine. A little now and then won't.

Run that by me again...?

roger, Roger, vector, Victor, over, Over

I must be blind or lucky, I've still not paid $2.00/gallon yet.

Kinda like:

"When a pack of smokes reaches ($2.00....$3.00...$4.00) a pack I'm quitting, that's it!! No more! I'm going to quit!!

Yeah.

:smoker

[SmithSR]

Tonight I paid $2.29 for 1 gallon of 92octane

Tonight I paid $8.66 for 1.2oz of Kodiak smokeless tobacco

It'll be quite some time before I complain about gas pricing.

[Jesda]

I run premium AND an octane booster.If you can afford a Q, you can afford the gas. If you can't, buy a Civic, and sell the Q to a more deserving owner.

Or park the Q and sputter around in a minivan, so you can still say you own one!

[louiegz]

I run premium AND an octane booster.

If you can afford a Q, you can afford the gas.

If you can't, buy a Civic, and sell the Q to a more deserving owner.

I agree 100%. You should use premium if it says to use premium. There's a reason they tell you to use it. The auto manufacture has no incentive in selling you expensive gas. I even noticed that when I had my Accord, it ran much better when I had premium than regular. If you compare fuel prices with the rate of inflation and what other countries pay for gas, we should consider ourselves lucky. You could move to Iraq and pay $0.60 for a tank full of gas but then there's nothing worth driving to over there.

[natsoundup]

still can get premium in SC in the 1.75 range.

[Aus94Q45]

Isn't the knock from the detonation and valves? Not really piston shimmy?

[psychic_mechanic]

Imagine your piston rocketing up the cylinder to squeeze your air/fuel mixture into an explosive mixture but while it is still moving up, the mixture lights off early. The piston is still going to move up when the explosion tries to push it down at the same time.

This is why detonation destroys engines. For a bit of great reading on engines in general, try "Power Secrets" by Smokey Yunick.

[psychic_mechanic]

By the way, there's a reason there is color pictures in the USA Today. They are aimed at a 4th grade reading level (Think AOL on newsprint)

[hannibal]

I read an article in Car and Driver a few years back about premium gas. They tested a BMW (I think) first on premium (as recommended) and then with regular gas. The performance difference was so small, they suggested sticking with the cheap gas.From my understand, these newer engines can 'read' the octane of the gas and the ECU can make the necessary changes. So running lower octane gas than recommended my decrease performance, your engine is able to adjust to it safely.

Manufacturers recommend higher grades to squeeze the last bit of power out the motor. I find it very interesting about Hondas and Toyotas using regualr gas while Acura and Lexus use premium.

[Q45tech]

For those that want to use regular, the easiest thing is to just retard your base time by 2-3 degrees [to 12-13 BTDC]. That way you won't be subjected to a sudden 5-10-15 degree retard when the KS sense knock when using regular.

At worst you will lose maybe 1 MPG on highway..........5% loss but a 10% savings on price [assumming 22 vs 21 @ $2.00 vs $1.80].

The 10% WOT power loss [15-27 HP/15-30 lb/ft] probably won't be feelable..........0.15-0.3 sec in total quarter mile..

Understand that at light cruise in 4th gear the timing may be in excess of 40 degrees to extend mpg........sudden throttle opening is unknown [as to exact amount in advance] so the ecu is always playing catch up........as the time for air to reach combustion vs the MAF reaction time........tip in throttle retard is signaled by the TPS rate of change [fast or slow throttle changes].......the transmission downshift lag adds to the problem.

Mostly knock is caused by carbon build up in chambers [raising compression ratio] and on valves [leaning the air flow] from not vigorously exercising the engine WEEKLY!

Eventually bad valve stem seals and rings let oil into the cylinders adding to the problem..........not understanding that the 4 year/60k plug change interval is only for a brand new engine, the 2nd might still be 60k, the 3rd 50k and the 4th 40k [the 5th [230k total@30k] ......depends on ring wear and driving conditionsTooo much bumper to bemper traffic and short trips.

[maxnix]

Isn't the knock from the detonation and valves? Not really piston shimmy?

Pre-detonation actually. Piston shimmy is a fantasy.__________________Brian1995 Q45 & Q45t & 2000 Q45

Discover the power of the button!

[Q45tech]

The piston must already be on the downstroke before the BMEP [pressure] builds sufficiently.

Ideally the maximum pressure occurs when the piston is 16-17 degrees after top dead center, [when the rod and crank are 90 degrees to each other] any earlier and the pressure tends to HAMMER the piston/thru rod straight down into the bearing instead of promoting rotation.Any later and the pressure never reaches optimum as the piston [and thus the combustion space] has gotten larger [thus less pressure.............both early and late timing reduces power.

Don't assume that every cylinder is exactly equal as variations in runners, and injectors and deposits [ change the AF ratio] thus some cylinders want earlier or later timing at different rpms.

The amount of advance is always that which works for the most knock prone cylinder. This tends to make that cylinder get worse and worse.

[driverdriver]

I wouldn't complain. You guys still have cheap gas. When I do the conversion from what we have up here to gallons, our prices work out to about $3 or $4 per gallon for mid grade, with some parts of Canada being more expensive.

Luckily I get to write off my gas, as a result I'm still using premium on the J but driving it less frequently.