Of course not, dont be silly!

 

Just figured I would post this directly from the 07 Jeep Service Manual to clarify a few things.

FUEL REQUIREMENTS
Your engine is designed to meet all emissions regulations and provide excellent fuel economy and performance when using high quality unleaded “regular” gasoline having an octane rating of 87. The routine use of premium gasoline is not recommended. Under normal conditions the use of premium fuel will not provide a benefit over high quality regular gasolines and in some circumstances may result in poorer performance.

Light spark knock at low engine speeds is not harmful to your engine. However, continued heavy spark knock at high speeds can cause damage and immediate service is required. Engine damage resulting from operation with a heavy spark knock may not be covered by the new vehicle warranty.

Poor quality gasoline can cause problems such as hard starting, stalling and hesitations. If you experience these symptoms, try another brand of gasoline before considering service for the vehicle.

Over 40 auto manufacturers world-wide have issued and endorsed consistent gasoline specifications (the Worldwide Fuel Charter, WWFC) to define fuel properties necessary to deliver enhanced emissions, performance and durability for your vehicle. We recommend the use of gasolines that meet the WWFC specifications if they are available.

REFORMULATED GASOLINE
Many areas of the country require the use of cleaner burning gasoline referred to as “reformulated” gasoline. Reformulated gasoline contain oxygenates, and are specifically blended to reduce vehicle emissions and improve air quality.

We strongly support the use of reformulated gasoline. Properly blended reformulated gasoline will provide excellent performance and durability for the engine and fuel system components.

GASOLINE/OXYGENATE BLENDS
Some fuel suppliers blend unleaded gasoline with oxygenates such as 10% ethanol, MTBE, and ETBE. Oxygenates are required in some areas of the country during the winter months to reduce carbon monoxide emissions. Fuels blended with these oxygenates may be used in your vehicle.

CAUTION: DO NOT use gasoline containing METHANOL. Gasoline containing methanol may damage critical fuel system components.

MMT IN GASOLINE
MMT is a manganese-containing metallic additive that is blended into some gasoline to increase octane. Gasoline blended with MMT provide no performance advantage beyond gasoline of the same octane number without MMT. Gasoline blended with MMT reduce spark plug life and reduce emission system performance in some vehicles. We recommend that gasolines free of MMT be used in your vehicle. The MMT content of gasoline may not be indicated on the gasoline pump; therefore, you should ask your gasoline retailer whether or not his/her gasoline contains MMT.

It is even more important to look for gasoline without MMT in Canada because MMT can be used at levels higher than allowed in the United States. MMT is prohibited in Federal and California reformulated gasoline.

SULFUR IN GASOLINE
If you live in the northeast United States, your vehicle may have been designed to meet California low emission standards with Cleaner-Burning California reformulated gasoline with low sulfur. If such fuels are not available in states adopting California emission standards, your vehicles will operate satisfactorily on fuels meeting federal specifications, but emission control system performance may be adversely affected. Gasoline sold outside of California is permitted to have higher sulfur levels which may affect the performance of the vehicle's catalytic converter. This may cause the Malfunction Indicator Lamp (MIL), Check Engine or Service Engine Soon light to illuminate. We recommend that you try a different brand of unleaded gasoline having lower sulfur to determine if the problem is fuel related prior to returning your vehicle to an authorized dealer for service.

CAUTION: If the Malfunction Indicator Lamp (MIL), Check Engine or Service Engine Soon light is flashing, immediate service is required; see on-board diagnostics system section.

MATERIALS ADDED TO FUEL
All gasoline sold in the United States and Canada are required to contain effective detergent additives. Use of additional detergents or other additives is not needed under normal conditions.

FUEL SYSTEM CAUTIONS
CAUTION: Follow these guidelines to maintain your vehicle's performance:

The use of leaded gas is prohibited by Federal law. Using leaded gasoline can impair engine performance, damage the emission control system, and could result in loss of warranty coverage.
An out-of-tune engine, or certain fuel or ignition malfunctions, can cause the catalytic converter to overheat. If you notice a pungent burning odor or some light smoke, your engine may be out of tune or malfunctioning and may require immediate service. Contact your dealer for service assistance.
When pulling a heavy load or driving a fully loaded vehicle when the humidity is low and the temperature is high, use a premium unleaded fuel to help prevent spark knock. If spark knock persists, lighten the load, or engine piston damage may result.
The use of fuel additives which are now being sold as octane enhancers is not recommended. Most of these products contain high concentrations of methanol. Fuel system damage or vehicle performance problems resulting from the use of such fuels or additives is not the responsibility of DaimlerChrysler Corporation and may not be covered under the new vehicle warranty.
NOTE: Intentional tampering with emissions control systems can result in civil penalties being assessed against you.

 

I tried telling the same story in another thread... I swear that I am getting better gas mileage out of mid-grade but instead of people trying it for themselves it seems they would rather just give their opinions instead. I have to agree that it would not make much since that a higher octane fuel would have better mileage than the reg's (because of all the science such as the lower compression engine and the faster igniting lower octane fuel and all). Therefore, I can totally understand how most of these comments are being made. But I challenge the doubters to at least try before they write again. This way some true real world experiences will be reflected in this thread instead of the strictly opinion based comments.

 

This thread was supposed to be dead...why did we have to bring it back?

 

Amen to that brother. I live in Denver, and I never use anything but regular. Total waste of money!!!:toung:

 

Um, so you lied about using premium?

 

I run 87 and the JK runs great, I lost 15 Lbs, and I gained 2.5" from head to change-purse.

 

I'd like to take this moment to point out a few things. Just some random thoughts.

I realize Carl was a moron in the movie, but I'm sure he had a double digit IQ. I think Speech requires something in the 30s (IIRC).

Wikipedia is NOT an accurate source of information about everything. (Not that CNN is much better), but there was a report on CNN today where they estimated the accuracy rate on wikipedia to be about 20% (and had support on the number from a nameless souce in the comapany). The other 80% is bunk (and therefore completely useful on this thread.)

You ran faster wearing the Reebok Pump shoe beacuse there were literally people trying to kill you to take your shoes. I don't have to run faster than the bear, I just have to run faster than my slowest friend that saw the bear with me.

 

Premium gas is amazing: I swear, my "member" grew 3" when I drank a gallon of 93 octane! Try it FR! (Not really).

Seriously, there is a TON of research out there which scientifically proves that higher-octane fuel in an engine that's "tight enough" to take advantage of it is just wasteful... the most recent article I read on the subject was in Maxim, of all places, but Car & Driver and others have also explored this myth and proven that 87 octane is just as good in lower-tuned engines (i.e. JK's 3.8L).

I'm paraphrasing here, but I believe the Maxim piece concluded along the lines of "So, running 93 octane in your [insert name of old POS here] only makes the terrorists richer."

 

Exactly my thought....die thread die!