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Wow, this thread suddenly went south fast. What does a Ford Crown Vic have to do with the OP’s question? And octane is a measurement not a thing, it cant “compress”; does nothing to answer the OP’s question....




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The question has been answered like 10 times!!! Run what ever you want!!! I personally run premium in mine for the reason I explained in my previous post. That's what is recommended, but apparently not required, per FCA. I don't mind paying a couple bucks more per tank full for the piece of mind. Top tier fuel only as well, because not all fuel is created equal, also explained in several previous posts...(- ;
 

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your engine, like any is based on compression. Octane compresses at different rates and has different flash-points. if your engine is designed for 87, run 87. if 93, yup run 93. If you have done mods (typically a lot of them not just intake and exhaust) then you may be able to run 93.
this video explains it nicely.
its not magic, its science. Running 93 in an engine designed for 87 would (over time) be very bad. running 87 in an engine designed for 93 would have similar results.
Where do you guys even find 93 octane at the pump? I travel all over the US, and the highest octane available at "regular gas stations" in America anyway, is 91. Now I do have a place I buy 100 octane racing gas that I use in my built LS7 equipped sand car, but it's not a gas station. Just wondering...
 

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Wow, this thread suddenly went south fast. What does a Ford Crown Vic have to do with the OP’s question? And octane is a measurement not a thing, it cant “compress”; does nothing to answer the OP’s question....
An octane rating, is the measure of how much compression the fuel can bear before detonating. Your engine, or any engine, has a specific compression ratio. The jeep cherokee has a 10.0:1 ratio the entire point of my comment was to say simply this...
If a vehicle is designed around a specific octane, you should never, unless the engine is heavily modified(changing out pistons and fuel management and more), change the fuel type(octane) recommended by the manufacturer. because..you will get spark knock. eg. the piston being forced downward by the explosion of fuel air mix and spark too early or too late in the stroke. In mild cases this will wear out parts, in extreme cases you can push one of the rods through the block. All gas powered engines operate under the same basic principle. fuel and air are mixed into a cylinder of a specific size and compressed by the piston in that cylinder, which is connected to a crank shaft. Once the piston is at top dead center the spark will ignite that mix and drive the cylinder downward. incorrect octane will cause that to happen improperly.

educate yourself and be amazed.

now, all that being said, modern engines come with knock sensors and can/will retard timing and adjust fuel curves within reason. the factory, and believe me they have done loads of research, recommends 91 octane. You can likely run 87 in it, with few issues; primarily lower performance and poor mpg.
a quick search of this forum yields loads of results on OP's question.

would i put 91,93 or even 97 in a engine not designed for it? Not in a stock engine, though i have in engines i have heavily modified. I built a 1995 z28Lt1 motor into a 383 stroker with 100 shot of nitrous AND and 9psi blower. the entire engine was taken apart and rebuilt. and yes it took 93 or higher. though it had over 700 horsepower.

TL;DR its your vehicle, do as you wish at the end of the day its on you if you break it.
 

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Where do you guys even find 93 octane at the pump? I travel all over the US, and the highest octane available at "regular gas stations" in America anyway, is 91. Now I do have a place I buy 100 octane racing gas that I use in my built LS7 equipped sand car, but it's not a gas station. Just wondering...
i havent had a need to look for it, though I have seen 93 here in NY (buffalo area) and while serving at FT. Bragg (fayetteville, NC) in the late 90's early 2000's i saw93 and 97 in pumps. you could buy 107 out of the pump trackside at rockingham(the drag way not the oval)
 

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Turbo you got that right lol. Here in SO CA the diff between 87 and 91 is $ .29 and that doesnt warrant any reason for me not to buy 91 and i am retired. With 87 my jeep will be running in retarded mode most of the time and mpg and performance will suffer and i cant have that lol.
 

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Where do you guys even find 93 octane at the pump? I travel all over the US, and the highest octane available at "regular gas stations" in America anyway, is 91. Now I do have a place I buy 100 octane racing gas that I use in my built LS7 equipped sand car, but it's not a gas station. Just wondering...
I’m in the Midwest and 93 is whats available has the Premium blend. I can’t find 91 to save my life.
 

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I’m in the Midwest and 93 is whats available has the Premium blend. I can’t find 91 to save my life.
Well damn, interesting.I'm in Nebraska right now, just checked the BP station, and 91 is premium here. In Utah we actually have 4 blends, 85, 87, 89, and 91. Maybe it's an altitude thing. Never seen 93 anywhere here out west higher than 91 for at least a couple decades. Cali, Arizona, Nevada, New Mexico, and I think even Oregon and Washington, all 91.
 

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Here are the gas prices at the top tier 76 station i go to here in SO CA as of 3/23/20.
87
$3.26
89
$3.40
91
$3.55
Wow, you guys are pretty low right now, only about $1.25 above the national average today!!! You guys are still getting seriously screwed in Cali as usual. The price of crude closed today at $24 a barrel. I saw regular unleaded at a Speedway station in Michigan on Saturday selling regular unleaded for $0.99 a gallon. That's about right for even the highest tax states.
 

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Well damn, interesting.I'm in Nebraska right now, just checked the BP station, and 91 is premium here. In Utah we actually have 4 blends, 85, 87, 89, and 91. Maybe it's an altitude thing. Never seen 93 anywhere here out west higher than 91 for at least a couple decades. Cali, Arizona, Nevada, New Mexico, and I think even Oregon and Washington, all 91.
I do think it’s an altitude thing. Back in 1989 I drove my ‘67 Mustang out to California and back. I was just a kid and didn’t know much but I knew enough to run the highest octane I could find for the V8. I camped out(thankfully at a campground) high up in Utah and the next morning was very cold for August. The darn thing would start for anything. A classic Mustang that wouldn’t start got a lot of attention from everyone at the campground when someone finally asked what fuel I was running. Someone pointed out I was an idiot for running premium up there and he gave me a can of 85 Octane to pour into the tank. After turning It over a few times it started right up. Ran 85Octane the rest of the trip without a problem until I crossed the Mississippi and the ”pinging” started. Back to high Octane.
 

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Discussion Starter #35
I have put 110 octane in a car that recommended 93 in the manual, and I can say it did nothing but a dent in my wallet. There are a few stations in Michigan that sell 110 octane unleaded. You can get even higher if you go to leaded.
 
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