In general there isn't much difference between 87 and 89 octane fuel. So you won't notice much difference in MPG's. However when you do start seeing a difference is when the is a higher milage on the engine. the 89 octane would be best to run with higher milage as it will help carbon build up in the engine which can drastically effect the performence of higher milage engines.

With that said it is also good practice if one is to run 87 octane that every 4th full tank fill with 89 octane. this again will help keep carbon build up minimal. with price of fuel the way it is the savings and this method wouldkeep the hemi happy :smileup:

 

Federal law requires all grades of gas to have the same additive package for cleaning. From brand to brand, they are different, but within a given brand, the additives are the same, regardless of octane rating. I think this law went into effect in the mid 90's. That's why you never see those commercials telling someone to purchase high octane gas for better cleaning of injectors, like years ago.

If you want a good additive package, fill up with a top tier gas brand... You can go to http://www.toptiergas.com/ to get more info on it.

BTW, higher octane is really now for higher compression engines. So if your manual says use 89 octane, but 87 is ok... You'll put out slightly less power on 87 octane fuel... Nothing that people will notice.

One other thing... When you see that pump that says 87 octane is the minimum dispense from a given pump, you better believe, you're getting 87 and nothing more... This I learned from an engineer (family member) that works in the oil refining industry. He told me, giving more octane than what's on the pump is called a giveaway and they are very strict on giving no more then the minimum octane rating.

 

I had a 2011 sport hemi and now a 2013 longhorn hemi and both only get 94 octane nothing less

 

Unless you have your engine tuned with a BD or a diablo, that is just a waste of money.

all the ECU is doing is modifying the timing of the engine and the fuel air mixture for the 93 octane, unless you have a tuner, you wont see any difference, it wont hurt your engine, just your wallet.

 

One thing to think about though, such a small percentage of people get 89 so there's no telling how old/clean the stuff is that you're getting.

 

Not really. I have been told, around here anyway, that the stations only have 2 underground tanks. One for 87 and another for 91 octane. The 89 octane is formulated at the pump by drawing equaly from the 91 and 87 tanks.

 

^ you are correct on the 2 tanks.

On several highway trips I used 92 octane fuel and 87, the 92 showed better mileage on the evic. And it makes sense as around here regular fuel (87) contains 10% ethanol

 

Exactly the reason why I only put 89 in my tank. :smileup: Besides I feel better using "recommended" over "acceptable". Just me.

 

i run 93 and have always run it in every vehicle ive owned with synthetic fluids

 

Synthetic will be in my ram for next winter, -40c mineral oils look like molasses.

91 is far from a waste of money, I get my money back with better mileage, like I said, and the cleaner fuel is just a bonus. The 4.7 might not benefit from the higher octane, but my last 2 hemi's did

 

It don't matter what displacement your engine has, running higher Octane fuel without adjusting the ECU to use that fuel will benefit nothing, not even Fuel economy.

Read Your Owner’s Manual

Unless your engine is knocking, buying higher octane gasoline is a waste of money. Premium gas costs 15 to 20 cents per gallon more than regular. That can add up to $100 or more a year in extra costs. Studies indicate that altogether, drivers may be spending hundreds of millions of dollars each year for higher octane gas than they need.
It may seem like buying higher octane “premium” gas is like giving your car a treat, or boosting its performance. But take note: the recommended gasoline for most cars is regular octane. In fact, in 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. Your best bet: listen to your owner's manual.
The only time you might need to switch to a higher octane level is if your car engine knocks when you use the recommended fuel. This happens to a small percentage of cars.
About Octane Ratings

What are octane ratings?

Octane ratings measure a gasoline's ability to resist engine knock — a rattling or pinging sound that results from premature ignition of the compressed fuel-air mixture in one or more cylinders. Most gas stations offer three octane grades: regular (usually 87 octane), mid-grade (usually 89 octane), and premium (usually 92 or 93). The ratings are posted on bright yellow stickers on each gas pump.
What's the right octane level for your car?

Check your owner's manual. Regular octane is recommended for most cars. However, some cars with high compression engines, like sports cars and certain luxury cars, need mid-grade or premium gasoline to prevent knocking.
How can you tell if you're using the right octane level? Listen to your car's engine. If it doesn't knock when you use the recommended octane, you're using the right grade of gasoline.
Will higher octane gasoline clean your engine better?

No, as a rule, high octane gasoline doesn’t outperform regular octane in preventing engine deposits from forming, in removing them, or in cleaning your car's engine. In fact, the U.S. Environmental Protection Agency requires that all octane grades of all brands of gasoline contain engine cleaning detergent additives to protect against the build-up of harmful levels of engine deposits during the expected life of your car.
Should you ever switch to a higher octane gasoline?

A few car engines may knock or ping even if you use the recommended octane. If this happens, try switching to the next highest octane grade. In many cases, switching to the mid-grade or premium-grade gasoline will eliminate the knock. If the knocking or pinging continues after one or two fill-ups, you may need a tune-up or some other repair. After that work is done, go back to the lowest octane grade at which your engine runs without knocking.
Will knocking harm my engine?

Occasional light knocking or pinging won't harm your engine, and doesn't mean you need a higher octane. But a heavy or persistent knock can lead to engine damage.
Is all "premium" or "regular" gasoline the same?

The octane rating of gas labeled "premium" or "regular" isn’t the same across the country. One state may require a minimum octane rating of 92 for all premium gasoline, while another may allow 90 octane to be called premium. To make sure you know what you're buying, check the octane rating on the yellow sticker on the gas pump.

 

I do listen to my owners manual and it recommends 89 octane, or the middle grade around here. I believe the 5.7 has higher compression than the 4.7, that is why I said your 4.7 wouldn't benifit from the higher octane. Also like I said 87, or regular gasoline in Atlantic Canada contains 10% ethonal, which hurts your mileage and if it sits for a month or so it'll attract moisture which isn't ideal.

 

Again this has nothing to do with the displacement of an engine, Engine Octane values for an engine are based on the Compression ratio, the 4.7 has a Compression Ratio 9.8:1, this engine can run on 87 Octane, the 5.7 engine has a compression ration of 10.5:1, its recommended Octane is 89. but can also run 87 without knocking. The reason the octane is 89 in the 5.7 is that with lower octane levels detonation is possible and will produce knocking in the engine. If you add a higher Octane fuel to any engine that is not setup to burn that type (having a Tuner will allow the modification of the ECU) of Octane level, you are basically just burning money out of your pocket, than in your truck. Now, If you tune your engine, (i.e. my 4.7l engine with a bully dog tuner) this will allow for the ECU to be configured to burn 93 Octane, This will also allow the engine to produce more hp because it is now configured to do so. But if you feel that it really does something for you in your truck, by all means, spend more for that fuel. As long as it makes you happy. :smileup:

 

Do the Hemi engines or their gas tanks have a "changeable" fuel filter, or is it one of those lifetime filters built into the gas tank?

 

You are reinforcing what I said. Higher C.R on the hemi recommends the 89 octane, I know displacement has no determination on octane requirement. I have a 440cc snow cross sled and it needs race fuel due to the very high compression ratio. This is why I'm stating the 4.7 doesn't require 89 because I know it has a lower cr. I have driven a 4.7 for 6 years In my work truck.

I see better mileage with supreme, like I said, and one thing you seem to be overlooking is the fact that regular gas where I live contains 10% ethonal, which we all know hurts fuel mileage, as my EVIC also tells me from my personal experience. So enough with the passive aggressiveness

 

Like I said, as long as your happy with putting more money on gas with higher octane and not changing anything in your truck, that's your prerogative. Do some recherche you will see, it adds nothing to your trucks engine unless you have a way to tell the ECU to use the difference. All the best.:smileup:

 

Non-serviceable lifetime Filter in the tank

 

Right on:smileup:

 

Oh by the way: Higher octane fuels burn slower so unless you can increase your initial advance (tuner) you will not see any difference. Also when a vehicle is tuned to use lower octane fuel a higher octane will create carbon deposits and over time will cause engine ware, overheating, and poorer fuel economy. Today's ignitions are computer controlled many are distributor-less so we shade tree mechanics can't mess with them. Many of today's vehicles recommend 91 octane but can use 89 or 87 if you don't hot rod them or over load them. Food for thought.

and all this information is taken from "American Petroleum Institute website"

http://www.api.org/ <---------- lots of good reading

http://www.consumer.ftc.gov/articles/0210-paying-premium-high-octane-gasoline

http://www.examiner.com/article/does-higher-octane-gas-improve-mpg-s

http://mechanics.stackexchange.com/questions/1494/will-higher-octane-fuel-improve-gas-mileage

http://www.nicoclub.com/archives/gasoline-octane-myths.html

http://www.carsdirect.com/car-buying/will-a-higher-octane-level-increase-a-cars-fuel-mileage

http://www.wanderings.net/notebook/Main/IsHighOctaneGasWorthTheMoney

http://www.whatcouldbegreener.com/142/fuel-octane-choosing-the-wrong-octane-will-cost-you/

 

Fact: ethonal lowers your fuel mileage
Fact: hemi engines recommend 89 octane
Fact: regular gas (where I live) contains 10% ethonal

Therefor I run 89-91 octane fuel

Fact: my evic show me gains in fuel mileage when running 89-91 octane, all else being equal.

Not a hard concept.

 

Very Scientific, Like I said, if it makes you happy to believe such things, a be it, its your money. Its your engine, its your prerogative, I am just giving the scientific truth of how things work in the real world for the other members to use.:4-dontknow:

 

I can copy and paste Internet links also if that would make it more scientific. Go surf the net for some more links to paste here, you must be a scientist? You crack me up. Have a good day.

 

I can copy and paste Internet links also if that would make it more scientific. You crack me up. Have a good day.

Go ahead, show me the science behind your Evic information, Lmao, your even funnier.

 

It agrees with the $ and litres I put in my truck, that's all the proof I need. It's hard to argue with someone who doesn't even own a truck with the engine we are talking about. Enjoy your day, I'm done with this

 

It agrees with the $ and litres I put in my truck, that's all the proof I need. It's hard to argue with someone who doesn't even own a truck with the engine we are talking about. Enjoy your day.

Lmao, nothing to back it up, ok no problem, but you can post the links up any time, it might help other members make there decisions on whether to spend more money on fuel than the benefits it can return. Its ok, this is what forums are all about, posting ones thoughts and experiences. I just feel bad for those who think that putting more Octane rich fuel in a vehicle that is not tuned to use it can get more mileage/to the cost of the fuel than just using what the manufacture Recommends. I once used to think the same thing and after doing much research and talking to many people have learned and grown. Imagine with that train of thought the Fuel Economy of a ram truck if you put racing fuel in your truck :SHOCKED:

 

I agree with that statement jrtz80. Mid grade 89 is derived from 87 and 91. 87 contains 10% ethonal so although minimal there is still ethonal in mid grade. I'll have to try mid grade and compare it to 87 in real world conditions

I was stating that 87 octane in a vehicle that recommends higher will yield lower fuel economy. For the reasons I already stated, ethonal being one of them.

Maybe that wasn't being clearly stated previously, but I thought I was being clear

 

I'm on the East coast too...just wondering if you have a source about our gasoline containing 10% Ethanol. I see a warning on the Ultramar pumps saying it "may" contain 10% ethanol, but I've yet to find any concrete info. Considering all gas at all stations around here either comes from Eastern Passage or Saint John, it shouldn't be too hard to confirm.

 

89 to 91 might yield better fuel economy, like I said ONLY because of the ethanol content in 89. That may or may not be true.

I was discussing the facts that 87 in a hemi will yield lower mpg than 89 or 91

 

89 to 91 might yield better fuel economy, like I said ONLY because of the ethanol content in 89. That may or may not be true.

I was discussing the facts that 87 in a hemi will yield lower mpg than 89 or 91

I agree with you. I think the main point was that higher than specified octane levels will not be benificial. I would personally not drop below the specified octane level unless I had too. Even though it works, I would believe that the engine is running its best at whats specified. When ethanol percentage is brought into the equasion it introduces a new variable. All things the same, higher octane alone will not yield better efficiency when the engine wasn't designed or tuned to take advantage of it. If anything it seems you are netting better results based on ethanol percentage rather that the octane level, when you go above 89 that is.

 

Agree 100%. This is what I'm saying, maybe that wasn't coming across. At over $1.35 a litre we're screwed at the pumps anyways

 

Now that's something I know we can all agree on, lol.

 

Sorry guys, if I touched a nerve with my post.

Here in Arkansas, we have 87, 89, and 91 octane I believe. What complicates matters even more, is we have 10% corn, 15% corn, then several stations now have what they call "pure" gasoline. The pure gasoline is 87 octane (I think)...I'm not sure I understand all the differences in fuel here.

And what's the difference in E85 versus 15% corn? Is it 85 percent gas, or 15 percent corn, or 15 percent gas and 85 percent corn?!!

 

15 percent gas and 85 percent corn?!!

yup 15 percent gas and 85 percent ethanol

E85, a mixture of 85% ethanol and 15% gasoline, is generally the highest ethanol fuel mixture found in the United States, as this blend is the standard fuel for Flex Fuel Vehicles. This mixture has an Octane Rating of about 94-97, which is significantly lower than pure ethanol, but still higher than normal gasoline

 

Is the 2013 Ram with Hemi a Flex Fuel Vehicle-can it run on E85? I would assume so, but I never thought to look for one of those green E85 stickers on the gas cap when I was test driving.

 

no, the 2013 Ram 4.7 and 3.6 is flex fuel. And I think the gas cap is supposed to be yellow for I guess corn color lol

 

That's how it's formulated around here. There are only 2 tanks at our gas stations, they get filled every Thursday and you can see the lids. One station even has 4 grades of gas all from 2 underground tanks

 

Maybe, I will stand corrected.....it wasnt that wat 15 years ago!

 

Mine will get 85 octane unless or until it pings. If that happens, it will get 87.

It's a pointless waste of money to run a higher octane than required and as long as it isn't pinging the octane requirement is being met.

Note though, altitidue reduces octane requirement and I live at about 4200 ft. - hence the 85 or maybe 87 and not even considering 89. The only vehicles I own that need higher than 87 are my old Triumph Bonnevilles with 12 to 1 pistons and air cooled aluminum heads.

- DAA

 

Dodge/Ram Fuel Mileage

I own a 2006 Dodge Ram Quad Cab 4.7L and a 2012 Ram Crew Cab 5.7L. Both have nitrogen filled tires and CIA's. And both have custom duel exhaust. I have tried 89 octane in both engines and have noticed a significant decrease in fuel mileage. The 4.7L showed an almost 2.5 mpg drop while the 5.7L shows a little over 1 mpg drop.

As far as engine knock or hesitation or anything else mentioned in the plethora of forums I've read concerning this issue with using 87 octane I haven't experienced any of it. I drive half highway half city miles. The 4.7L averages 15.5-16 city, 18-19 highway. The 5.7L averages 17-18 city, 20 highway.

I didn't buy either truck for the fuel mileage but I don't race them either. The MDS on the Hemi on or off doesn't show much difference in overall mileage but the performance is different in that the truck doesn't hesitate between gears as much or rev high when hitting the hills when the MDS isn't used.

I take it easy when driving but I know the power is there when I need it. I think the way today's engines are engineered they are more sensitive to driving habits and good maintenance practices. Trying to figure out which octane to use from which station is enough to drive anyone nuts.

I use a fuel additive every time I fill up but won't use it if there is a half tank or more. That's just personal preference. So, I guess, the takeaway from my post is drive a little easier, do the proper maintenance when it's needed, check tire pressure and fluid levels, and don't obsess over mileage. It fluctuates and always will no matter what you try.