premium fuel on sxt???

[proxyx99]

Manual says:
2.7L - 87
3.5L - 87 to 89
5.7L - 87 to 89
(nothing about "recommended" fuel)
downloaded PDF Owner's Manual from Dodge.
Section: fluids, lubricants...
So what's the conclusion? Where's the truth? Does Dodge even know?
Seems both grades are OK. And who cares about that 5.3 extra HP, haha...

[fordculater]

I've tried 87 in my tank and I get lower MPG's than 89. Onetime my check engine light came on. I'm sticking with 89. It's worth the extra $1.50 per tank.

[spinnercj8]

I have been using 87 in mine and have 73,000 on it and have had no problems, I will run premium every couple of months but mileage doesn't change!

[lawndoc012]

I have been using 87 for 60k and have had no problems. I am going to try 89 and see if there is a difference.

[QuickSilver08]

I rock the 89. Yeah, its a little more....but not so much as it breaks the bank. Im just glad that I dont use 93 on a car that gets 15mpg any more (last show car)

[crucian]

Same here I realized a diffrence in MPG after I switched to 89 octane,

[crucian]

Now I just need to get the engine breathing with an CAI system and air silencer removal

[proxyx99]

the point is: if the owner's manual doesn't say clearly to stick to 89 octane then both are ok, at least it seems this way. Factory mpg rating was done based on which one then? If it was: fuel: "89 octane (87 acceptable)" it would be different I guess, but can't find it anywhere. Isn't owner's manual a place to say it clearly so users know? Lastly if the pref. is on 89 side then why is it "87 to 89" not "89 or 87". That would send clear signal. Nothing about 87 affecting warranty or performance. Elswhere yes, but not from Dodge. I'm new to Magnum and trying to figure it out...

[Giantchief]

We don't have 89 in Colorado, but mid-grade is best

[cksteele79]

What is octane? The concept of octane is peculiar to many people, including myself. I can't see it, I can't hold it, I can't buy it by itself, but I know I know I pay extra for it if I want more than 87 of it in my gas. Today we take an in-depth look at what octane is, and what significance a gasoline's octane rating has with regards to a supercharged engine.
The Simple Definition
An octane rating (87 vs. 89 vs 92, etc.) is a measure of a gasoline's ability to resist detonation, which manifests itself in a pinging or "knocking" noise. Higher numbers indicate that the fuel can be compressed to a higher level before detonation / knock occurs in an engine, which occurs when. As described in "Detonation, Knock, and Pre-Ignition 101", detonation / knock occurs when air and fuel that is ahead of the combustion flame front ignites before the flame front arrives.
The Complicated Definition
Octane is actually more than just a rating - it is a hydrocarbon just like methane (single carbon atom), propane (three carbon atoms), butane (five carbon atoms), and heptane (seven carbon atoms). Octane (C8H18) is a hydrocarbon with eight carbon atoms and eighteen hydrogen atoms. 100% octane fuel is remarkably resilient to compression (i.e. it does not combust when compressed) and is thus resilient to detonation / knock. This resilience is derived from the branching of octane's carbon chain (see figure). Because of the nature of octane as being resilient to detonation, all fuels are compared to 100% octane as a benchmark fuel, from which an "octane rating"can be obtained. Heptane, a hydrocarbon with seven carbon atoms, compresses very poorly and spontaneously combusts even under small amounts of compression. In other words, Heptane's behavior when compressed is diametrically opposed to Octane's behavior under the same conditions. For this reason, Heptane (which has an octane rating of zero) is the other benchmark fuel used in the octane rating system to determine a fuel's octane rating. A fuel that spontaneously combusts (knocks) under the same amount of compression as a fuel composed of 87% octane and 13% Heptane would have an octane rating of 87. This is not to say that 87 octane gasoline is made up of 87% octane and 13% heptane, rather that the 87 octane gasoline "knocks" in a laboratory knock engine at the same compression ratio as a fuel composed of 87% octane and 13% heptane.

The coomposition of an octane hydrocarbon.
Unfortunately, it gets even more complicated. Because various fuels respond differently under varying engine loads, a gasoline may get a different octane rating on a free running engine and one under load. For this reason, the octane rating label that we see at the pump (monitored by the U.S. Cost of Living Council) is actually an average of two octane ratings - the motor method rating (where the engine is run under a load) and a research method rating (where the engine is run freely). The formula used to get the CLC Octane number on gas pumps in the United States is thus: (Motor Octane Number + Research Octane Number) / 2.
What's the benefit of higher octane?
Higher octane fuel has only one beneficial feature - it allows an engine to run at higher temperatures with more advanced ignition timing under higher levels of compression witout detonating / knocking. Higher octane fuel does NOT have more potential energy and will not make an engine perform better unless that engine is knocking. On modern engines with knock sensors, higher octane fuel may make the engine run better if the knock sensors are retarding the ignition timing, which hinders performance. High octane fuel does not burn cleaner, it does not clean your engine, it does not increase horsepower or torque (unless you are experiencing knock), it does not smell better, it does not increase fuel economy (unless you are experiencing knock) and is not better for the environment. If you buy higher octane fuels for any of the above reasons, STOP!
When should I switch to a higher octane fuel?
First off, never run lower octane fuel than is recommended by the vehicle's manufacturer. If the vehicle manufacturer recommends 89 octane gasoline, this means that the engine has been tuned to perform optimally without detonation on 89 octane fuel. Once you've done some modifications to your engine, the manufacturer's recommended gasoline may no longer suffice. Obviously, if you can hear detonation inside your engine in the form of pinging or "knocking", try a higher octane fuel. You will also need to run a premium grade fuel (91+ octane) if you have a supercharger, turbocharger, or if you have an ignition programmer that advances your ignition timing.







well i found this hope this helps