duneslider

You will probably cause carbon buildup by running higher octane gas because it won't all burn off leaving the chamber too cool for proper/full combustion. Don't worry though, if you really want to run 91 you will have enough carbon buildup after a while to require the need to run 91.

It's called premium not because its better but because you pay a premium.

trbizwiz

Is this urban legend? Is this based on any real evidence? Would it not be better to run the recomended fuel, and if your engine needs cleaning, run a fuel system cleaner through it? Randomly paying a 20% premium for non recomended fuel sounds a bit naive to me, even if it does have special cleaners, they would not be as concentrated as a bottle of cleaner added to the propper tank of fuel.

Yasoonb

Let's not forget that the recommended fuel for the jeep is 87. That means it was tested and tuned specifically for 87 running anything else would make it run differently than what jeep intended. Now I'm not saying run better or worse.

jeeeep

unless you have a programmer to adjust for the higher octane, run 87.

If you think you're gettign dirty gas or rough idle add a cleaner.

Before I got the Superchips, i ran cleaner about every 5000 miles (usually when I noticed a rough idle) with 87 gas, no issues 40,000 miles later.

i still use cleaner even with tuner and 91 octane,

JamesWyatt

Couple of things here. All things being equal, higher octane gas actually contains less energy and will not increase your mileage. However, all things are not always equal, and high octane gas may contain less Ethanol and provide a modest bump. I drove a Prius for 4 years with a long daily commute, and I can tell you that when you're talking a small percentage change in gas quality, it translates into a much bigger difference when your vehicle can is hitting the 47-52 MPG range. Just the change from summer to winter gas blends every year had a big impact. FYI Shell makes some of the highest energy gas out there. There are others, but I always got better results with Shell gas.

I've found with my Jeep, it seems to like 91 better. More power. No pings. Probably less ethanol in the 91, and I get 2 more miles per gallon consistently. It may say you can use 87, but I am highly suspect that the engine performs best with it. It would be a huge sales hit if on top of 15-17 MPG, they also told you to run premium gas.

JamesWyatt

They are actually great vehicles after you pick them up and shake out the driver.

yo_marc

I run 87 here in New England, almost full time. I will go to 91 at times in the summer months if I find that the Jeeps pinging more than I like.

I used to run whatever brand of 87 was cheapest in town. I have since been committing to a name brand station. The quality of fuel there has been very consistent.

FWIW, I definitely agree that if you don't need to run a higher octane (on a stock motor, on stock programming) to fight detonation, you won't gain anything. However, if you're running 87 and pinging, switching to a higher octane 'will' - at least in my case - increase mileage. Engines with knock sensors will retard ignition timing to fight detonation - that's not conducive to power or economy. That's why you'll hear it stated in the manuals for cars designed to run premium, (something like) "If 93 octane is not available, running a lower octane will be ok, but engine performance may be degraded".

Krynn

Let me clarify: I was not referring to octane with that statement. Cheap gas = WalMart, RaceTrac, BubbaJoe's QuickieFuel, etc. High-quality gas = Chevron, Exxon, Shell, etc. The fuel that you get at the discount gas stations are cheaper for several reasons, one of them being that they don't add fuel system cleaners to their gas, regardless of what octane level it is. And more often than not, the difference in price is less than the cost of of a fuel system cleaner additive. Wal-Mart (Murphy USA) for example, has at many of their stations the ability to purchase additives at the pump, but the additional cost can make their fuel more expensive than the Chevron next door.

As for the advantages of running fuel system cleaners through your engine versus running name brand fuel, well, that's up in the air. What's better, paying an extra $1.50 or so per tank of gas, or paying about $9 every 3000 miles or so? The fuel additive works out to be a little cheaper over time, but I find it easier to just use quality fuels with the additive already in it and not worry about it. And since I'm running a stock engine tune, I just use whatever grade works out to 87 octane.

Ryan0260

I run ethanol free gas. There is only one local place that sells it. I'm pretty sure they don't put fuel cleaning additives in it though...

JK-Ford

Well I remember when regular gas was $0.50/gal. And I remember when regular gas would gum up the fuel system! I know that fuel has improved since the good ole days. But I still believe that mid-grade gas is better for an engine than low-grade gas. Reguardless of the tune.