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Which gas would you use for your JK?

7K views 25 replies 20 participants last post by  Thunderjet 
#1 ·
I live on a lake and as a result of boat traffic there are several gas stations within a few miles of my house that sell ethanol free fuel. All of these stations are small local outfits (not Shell, Exxon, etc.) but have 100% gas.

I have a new JKU, and I'm about to need to fill up for the first time. If you had easy access to ethanol fee gas at a local Mom and Pop type station vs big name station with fancy detergents and additives but with ethanol, which would you use?
 
#3 ·
is that ethanol free gas marked for use strictly by boats, lawn mowers etc. Most stations frequented by boaters sell premium gas which has no road tax on it and is not legally for sale for motor vehicle use
 
#4 ·
No, it's available because of all the boats, but not marked for use only by boats, mowers, etc. Plenty of people filling up their cars and trucks with it. The stations that have it, advertise "100% Gasoline Here!" Or similar but no restrictions mentioned.
 
#5 ·
If you have it available use it. No reason to use anything higher than 87 octane unless you are noticing knock. Throw in a bottle of Techron every now and then and you will be golden.
 
#6 ·
Boating fuel does have highway taxes on it. If you boat a lot you can file for a tax refund. Some types of aviation fuel do as well. That's the reason it can be purchased legally without owning a boat or aircraft. However, it's illegal to run leaded aircraft fuel like 100LL on public roads and the cats would need to come off as well. Higher than recommend octane won't produce more power without a tune. It could possibly run the engine cooler, but that would be dependent on how the ECU handles it.
 
#9 ·
Boating fuel does have highway taxes on it.
Not necessarily. Likely varies by state, but in MI and FL, marinas sell reduced tax fuels right at the dock or pier, but most (all?) standard gas stations selling marine fuel will likely have taxes applied to the cost because people would be using it for their vehicles as well as marine applications.

Otherwise, I think I concur with all other statements. :)
 
#13 ·
Anyone who has owned a later TJ knows what alcohol can do to your check valve. I had a problem with a bad ping and started pumping 93 or 91 no ethanol fuel. It is available right at the gas station. Think about going back to 87 but it's cheap insurance. Also run it in the 25 year old snowblower.
 
#18 ·
THIS ^^^^^^^^^^^^^^^

If you are going to burn off the fuel within 90 days it's a non issue. The main draw back to ethanol is that it attracts moisture. Leaving it sitting in the tank for an extended period isn't a good idea. And the idea that it attacks and deteriorates rubber hoses and such is a non-issue in any engine built after 2005 or so. The materials used in later engines are designed to tolerate ethanol.

End result: If it makes you feel better, use it. If you think it burns better, use it. If you think you're feeling better performance, use it.

But none of the above are true when you get down to modern science and the fuels that we have offered to us.

As for octane, someone said that higher octane than the engine requires is a waste of money. This is true. In reality, the higher the octane the slower the fuel ignites and the more spark it requires to fully burn. Higher octane in the stock Wrangler engines is definitely a waste of funds, and could actually result in poorer performance than 87 octane. Not my opinion ..... just proven facts.
 
#26 ·
I seen a lot of stations in Nebraska and Colorado that sell 85 octane. Never seen it that low, is this a common octane across the country?
It is common at higher altitudes. Less air density means lower octane. Also, for every 1,000 feet of altitude then general rule is your engine loses 3% HP.
This is also way you cant find 93 octane in these states. It simply isn't needed. When we lived in Colorado Springs we ran 85 in our Tundra and Camry as well as our RV (Ford V10) with zero issues. If your engine normally requires 87 then 85 is perfect at higher altitudes.
 
#21 ·
Using a quality gas does more than just octane. Your best way to test what octane your jeep likes is a decent gas mileage test under common conditions. If your jeep likes a higher octane then your mileage will go up as the knock sensor will not be retarding your timing. If it doesnt then you dont need to go up that grade. AAA recently released a study of brands and made a list of ones that showed an ability to keep intake valves cleaner.
 
#25 ·
Good points. However you do not need to purchase the detergents in the gas. You could always run the cheap gas and throw a bottle of Techron in every now and then. That or BG Products 44K works very well but you want to run a tank of that stuff right before your next oil change.

There may be other good fuel system cleaners that you can pour into the tank.

edit: Me? I am spraying water methanol down my intake so I can run cheap crappy gas. It serves as an octane booster and cleans the out the motor. There would still be benefit from tossing a bottle of techron in the tank from time to time to clean the injectors.
 
#24 ·
My options in my area are 93-89-87. I have been putting 89 in mine. Right now I'm experimenting with what brand of gas runs best since owning my Jeep. Shell, Chevron, Exxon, Texaco... etc etc
A store down the road sells ethanol-free gas but he takes cash only and like posted above I only get it for atv's, boats, etc, that might sit up a while between use.
 
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