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Author Topic: what the diffence between premium gas than regular Back to Topics
brazilianguy

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Orlando

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Message Posted: Nov 11, 2013 5:29:14 PM

please somebody can help me.
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hoopitup2000
Champion Author Virginia

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Message Posted: Apr 12, 2015 7:13:06 AM

Premium is unnecessary for most drivers.
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dontuknowOH
Champion Author Ohio

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Message Posted: Apr 12, 2015 7:03:10 AM

Difference is Reading the vehicle's Manual = Wishing thoughts.....!
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twt
Champion Author Virginia Beach

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Message Posted: Apr 12, 2015 6:31:53 AM

Premium, is higher octane.
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RalphHightower
Champion Author South Carolina

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Message Posted: Apr 12, 2015 5:34:51 AM

the price and the octane
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GustheCat2
Champion Author San Antonio

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Message Posted: Apr 11, 2015 3:53:32 PM

About .20 per gallon
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dontuknowOH
Champion Author Ohio

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Message Posted: Apr 11, 2015 9:36:08 AM

I sure can't add anything to what philnTX posted, but I do believe premium comes out tailpipe faster, more so than does reg. grade when to be feeling performance, Hint...... $$$$ are side affects.....HMmmm.
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KLR56
Rookie Author Illinois

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Message Posted: Apr 11, 2015 6:26:07 AM

Higher Octane.
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twt
Champion Author Virginia Beach

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Message Posted: Apr 11, 2015 6:17:09 AM

How long have you been driving? The difference, is that Premium is higher octane.
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GLM4205
Champion Author Toledo

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Message Posted: Apr 10, 2015 11:10:09 PM

Octane
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PhilnTX
All-Star Author Dallas

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Message Posted: Apr 10, 2015 10:59:51 AM


EVEN at the cheapest petrol station in your correspondent's neighborhood, filling up the family kidmobile with premium (91 octane) fuel now costs over $70. As the meter clocks up dizzying dollar amounts, he looks longingly at the regular (87 octane) pump. Switching from his vehicle’s recommended premium-grade fuel to the cheaper variety would lower his fuel bill by at least 20 cents a gallon (more than five cents a litre). The question is, would it be worth it?

On the surface, the decision appears easy. Because the name “premium” implies a souped-up fuel that packs an extra punch, many motorists actually believe it delivers more oomph or miles per gallon—and may therefore represent good value. The truth, however, is that premium contains no more energy than regular petrol—around 114,000 British Thermal Units per gallon, depending on the season, the region, the local pollution requirements, and the amount of bio-ethanol that has to be added to petrol in America by law to keep the country’s corn-growers in clover (see “Competition at the pump”, August 20th 2012). The difference between premium and regular petrol lies in the blend of hydrocarbons used to make the fuel, and the package of additives mixed into it.

Nowadays, petrol is made up of hydrocarbons (mainly paraffins, naphthenes and olefins) produced in a catalytic cracker or reformer. The refinery process breaks the crude oil’s large hydrocarbon molecules into smaller ones by vaporising them in the presence of a powdered catalyst (an absorbent mineral such as zeolite). The blend varies depending on where the crude came from, the refinery equipment used, and the grade of petrol being produced.

Additives are included to reduce carbon build-up inside the engine, improve combustion, inhibit corrosion and allow easier starting in cold climates. Fuels that meet the requirements for “Top Tier Detergent Gasolines” (a voluntary standard endorsed by BMW, General Motors, Honda, Toyota and Volkswagen) contain more detergent in their additive packages than the minimum required by the authorities.

Another key additive that blenders stir into their brew is ethanol. That is done these days primarily to boost the fuel’s octane rating. A higher octane rating allows an engine to use a compression ratio of, say, 12-to-one instead of a more usual ten-to-one. The greater the compression, the higher the temperature within the combustion chamber. And the higher the temperature, the greater the thermal efficiency and power produced. In a nutshell, high-compression engines designed for performance need high-octane petrol.

Though ethanol has less energy per gallon than petrol, it has a considerably higher research octane number (RON)—around 108 to premium’s 97. It should be noted that this is not the octane rating seen on the pump in America. The RON figure results from a laboratory test done using a special engine with a variable compression ratio.

In the fuel test, the compression is raised until the engine begins to “knock”—ie, the fuel in the cylinder ceases to burn smoothly and instead detonates before it can be ignited by the spark plug. The cylinder pressure at which this occurs is then compared with that achieved while the engine is running on a reference fuel (a mixture of iso-octane and n-heptane). The ratio of the two pressures provides the RON of the fuel in question.

A better way of measuring a fuel’s ability to resist knocking under load is the so-called motor octane number (MON) test. This uses a similar test engine, but with a preheated fuel mixture, a higher engine speed and variable ignition timing. Because it uses more real-world conditions, the MON rating is typically eight to ten points lower than the equivalent RON figure.

Whatever the test, the point is that knocking needs to be avoided at all cost. If allowed to continue, it can quickly cause an engine to disintegrate. That is because when the air-fuel mixture in the cylinder detonates spontaneously before reaching the top of its compression stroke, the rising piston confronts a wall of rapidly expanding gases from the explosion, which attempt to force the piston back down the cylinder. The stresses caused by suddenly trying to reverse the rotation of the engine can become high enough to shatter the pistons, connecting rods and parts of the crankshaft.

To prevent that happening, a high-compression engine uses a blend of hydrocarbons that is somewhat less combustible than normal. Ethanol has an auto-ignition temperature of 362ºC, while petrol bursts into flames without a spark between 246ºC and 280ºC, depending on the blend. Therefore, adding a little ethanol to petrol can raise the auto-ignition temperature enough to prevent the blend from igniting purely from the heat generated during compression.

On the face of it, then, a motorist would seem ill-advised to use regular petrol in a car with a high-compression engine. That was certainly the case in the past. But cars today have sensors that listen carefully for the knocking sound, and instantly retard the ignition system when they detect that detonation is about to happen.

The delay in delivering the retarded spark allows the piston to start moving downward on its expansion stroke before the ignition actually occurs. That provides additional room in the cylinder head for the gases to expand and thereby reduce their damaging peak pressure—and so burn in a more controlled manner.

To sum up, if the car’s handbook says that premium petrol is “recommended” (rather than insisting it is “required”), then the engine will automatically adjust itself to run smoothly on a lower octane fuel. Because of the retarded ignition, the engine will, of course, produce less power, and have slightly higher fuel consumption. But the poorer fuel economy is likely to be outweighed by the savings at the pump.

Even so, your correspondent remains reluctant to make the switch. One reason is that no one has been able to tell him what damage is done, if any, by running the engine permanently in a retarded state, and forcing the anti-knock system to remain active all the time.

Another reason is because all the vehicle’s emissions testing was done using the recommended grade of fuel. Despite the fact that modern fuel-injection systems adjust the air-fuel mixture for changing conditions, your correspondent still has no idea how much more pollution the car might dump into the atmosphere if he switched to regular. Premium certainly has a better additive package, which helps keep the tailpipe clean as well as the inside of the engine.

But his biggest reason for sticking with premium, though, is that he was well aware that the car needed 91 octane to work properly when he bought it. And having paid upfront for the higher performance, he is reluctant now to throw that benefit away.

As for those who earnestly believe (and quite a few do) that filling the family Toyota with premium will somehow make it go faster or deliver more miles to the gallon, all one can say is don’t bother. As one wit noted, the only thing it will make run faster is money from your pocket.
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dontuknowOH
Champion Author Ohio

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Message Posted: Apr 10, 2015 6:07:47 AM

For some drivers, it reflects the amount of "Green" that stays in ones wallet, when at the refuel pumps.

Most modern vehicles, their ECM system will retune the engine's operation as the driver makes their choices in traffic. HQ HP. Engines will produce a better % of performance with the right spec. fuel when(hammered at the Go Pedal)for aggressive driving.....ACTS! & some extra "Green" maybe?
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f64
Rookie Author San Diego

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Message Posted: Apr 9, 2015 3:29:40 AM

Marketing hype!
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GuzzleMeThis
Rookie Author New York

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Message Posted: Apr 8, 2015 7:37:41 PM

A few cents per gallon.
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Bartlettvanman
Sophomore Author Memphis

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Message Posted: Apr 22, 2014 9:08:57 AM

Price. Doubt if you will see a big increase in gas mileage, but the car should have more pep and burn cleaner if you use it on occasion.
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Skyjunky
All-Star Author Portland

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Message Posted: Mar 20, 2014 6:23:33 AM

None.....Just buy non-ethanol...and buy LL regular.
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RalphHightower
Champion Author South Carolina

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Message Posted: Mar 20, 2014 6:00:34 AM

price and octane
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twt
Champion Author Virginia Beach

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Message Posted: Mar 20, 2014 5:04:06 AM

Too many to list, here. Follow your owner's manual instructions.
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dontuknowOH
Champion Author Ohio

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Message Posted: Mar 20, 2014 5:02:40 AM

The extra cost makes you think you have a tiger in your tank, without seeing the tail, read your operation manual and then see if it mentions (Lead-foot). Under-hood look for the words HO, Turbo Power, Super/Charged, Torque Boost, HO Ram/Charged, DOHC Turbo, in (Bold Lettering), buy a manual maybe. GoodLuck!......
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rrtruck
Champion Author Austin

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Message Posted: Mar 19, 2014 9:24:51 PM

Basically, the timing can be adjusted for more power with premium and still not ping.
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Kyun7
Sophomore Author Seattle

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Message Posted: Mar 19, 2014 2:38:53 PM

besides price?

plenty of explanations here:

https://www.google.com/search?q=lubro+molly#q=difference%20between%20regular%20and%20premium%20gas
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redfish67
Champion Author Dallas

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Message Posted: Mar 19, 2014 10:31:16 AM

a lot of wasted money
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luvmyrv
Champion Author Winnipeg

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Message Posted: Mar 11, 2014 12:24:06 PM

about 15 cents a litre...in Canada premium fuel has no ethanol.
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Awing1
Champion Author Ontario

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Message Posted: Mar 11, 2014 11:33:30 AM

Price and octane.
Does premium gas help improve gas mileage? Not sure.
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Saab93turbo
Champion Author Washington

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Message Posted: Mar 11, 2014 11:08:39 AM

In a few brands, the antideposit additive levels are higher in premium. Shell does this. Chevron does not. Source is the company's website
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pilotdlh
Champion Author Minnesota

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Message Posted: Mar 6, 2014 5:34:46 PM

A friend of mine used to work at a local refinery. He said they only made premium and sold it for premium or regular pumps. It was more costly for them to make two grades of gas than to make everything to the premium specs and sell it for the regular price.
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RalphHightower
Champion Author South Carolina

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Message Posted: Mar 6, 2014 5:59:37 AM

octane and price
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herbiepopnecker
Champion Author British Columbia

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Message Posted: Mar 6, 2014 1:27:37 AM

It's made from upper class dinosaur juice
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mhradecky
Veteran Author New York

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Message Posted: Mar 5, 2014 9:15:43 PM

93 burns hotter and cleaner.
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weddy11
Champion Author Phoenix

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Message Posted: Mar 1, 2014 9:59:42 AM

26 cents a gallon more or less
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dieselpower2014
All-Star Author Atlanta

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Message Posted: Feb 28, 2014 12:52:12 AM

octain
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JimBlake56
Veteran Author Akron

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Message Posted: Feb 20, 2014 1:49:20 PM

Premium is "higher-octane-rating" fuel, & "octane" is an old-fashioned word for the anti-knock index. Measured by a lot of different test procedures depending on the rules of the country you live in.

A whole lot of answers in this thread are correct about the main thing. Use what your car's owners manual calls for. Higher "octane" fuel doesn't do any good. And for a majority of cars that call for premium fuel, using regular will simply lower the power of your engine, but not do any damage.
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luvmyrv
Champion Author Winnipeg

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Message Posted: Feb 15, 2014 8:15:26 PM

In Canada premium has no ethanol.
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krazkar
Champion Author Calgary

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Message Posted: Feb 15, 2014 6:49:43 PM

It costs more. If your car doesn't require it, don't spend more for it
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Boyrr
Champion Author Allentown

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Message Posted: Feb 15, 2014 6:11:58 PM

It cost more
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Hemond
Champion Author Providence

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Message Posted: Feb 15, 2014 8:26:43 AM

This is a basic question and yet no one on this board has given a clear and satisfactory answer.
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redfish67
Champion Author Dallas

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Message Posted: Feb 3, 2014 10:00:44 AM

20-30 cents a gallon
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Bowlerman10
Sophomore Author Fort Worth

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Message Posted: Jan 28, 2014 1:15:35 PM

In todays cars, very very little to no difference. A well known car expert in the DFW area puts regular in his Acura that calls for premiam. The car runs great by his own words.
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MertieMan
Champion Author Lexington

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Message Posted: Jan 28, 2014 9:09:08 AM

The higher octanes run hotter in the engine. Only use what your owners manual specifies.
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bluenvoy
Champion Author Nashville

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Message Posted: Jan 27, 2014 10:03:13 AM

Put the fuel in that your owners manual says to.
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Boyrr
Champion Author Allentown

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Message Posted: Jan 27, 2014 6:10:31 AM

needed for engines that have higher compression.
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pghbill
Champion Author Pittsburgh

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Message Posted: Jan 27, 2014 12:23:35 AM

about 20 to 30 cents more
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cv
Champion Author Raleigh

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Message Posted: Jan 27, 2014 12:07:24 AM

High octane gas actually has a lower ignition point, thus prevents engine knock when the engine has higher compression. It is no "better" than regular octane.
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GuzzleMeThis
Rookie Author New York

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Message Posted: Jan 7, 2014 5:03:01 AM

Higher octane burns through your money at higher rate of speed.
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GLM4205
Champion Author Toledo

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Message Posted: Jan 6, 2014 4:45:13 PM

Price
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dontuknowOH
Champion Author Ohio

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Message Posted: Jan 3, 2014 2:04:05 PM

Like buying a more expensive Broom, later you will like it or wish you hadn't bought it, time will tell. How about work gloves?
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hyeglenn
Champion Author Fresno

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Message Posted: Jan 3, 2014 10:16:14 AM

Just the price.
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gvan
Champion Author Chicago

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Message Posted: Dec 25, 2013 12:11:07 PM

Forty cents difference is not uncommon.
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RS101
Champion Author Minnesota

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Message Posted: Dec 25, 2013 9:15:03 AM

Merry Christmas
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dontuknowOH
Champion Author Ohio

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Message Posted: Dec 13, 2013 8:16:48 AM

The Flash point is a higher in cylinder temp to prevent pre-detonation(going explosive)before the timed firing of the engines spark-plugs.

Lower octane has a lower temperature flash point for lower compression designed engines and possible a slower burn cycle on expansion pressure.

High performance designed engines work on the mid/extreme limits of their RPM range often.

Lesser designed engines are more dependable for the long haul of most moderate/medium/seldom extreme but lengthy work loads for the average purpose, needing less tuning. Less expensive fuel quality to maintain.
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ricebike
Champion Author New Jersey

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Message Posted: Dec 13, 2013 12:45:04 AM

is google search broken?
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RS101
Champion Author Minnesota

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Message Posted: Dec 9, 2013 7:32:40 AM

about 20 to 60 cents.
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