93 Octane! I like it!

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I have to believe if the higher octane was beneficial (mileage or power) Jeep would take advantage of that. I don't know all the ins and outs of federal mpg testing, but if there was scientific, measurable difference, Jeep would recommend the higher octane and claim the better mpg. Until then, I will continue to use 87 unless I hit the premium gas button by accident (which my other car recommends)(and other cars for the last 10 years).

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[TexasJeeper]

Ok..I am not an engine timing expert but if any of your JLUs Penstar 3.6s are like mine, it has a tendency to knock a lot. The colder the weather...it seems more prevalent. The key take away for me after watching this view was the computer controlled knock sensors reduce output.

Just saying...for those of us who have tried 93....its make no sense to go back to 87 with gas prices as high as they are. But for those saying 93 octane should not make a difference, I believe you are right. I am of the mind set that 87 just produces too much knocking and the knock sensors and computer protects the engine by reduces output and thus consumes more gas for less performance. Ugh.,

If your 3.6 knocks more when cold then it's an issue with the engine. Most of the time when you say knock that means spark knock, aka pre-detonation. Colder air deters spark knock.

 

[Markham]

Because that's Canadian fuel, eh?

Lol I didn’t know. But then again most people think Maine is part of Canada

 

[ZEN357]

I run 87 through my daily driver with no issues, but a I always run 93 through my through my Challenger.

 

[WXman]

There's a lot of hatin' going on in this thread, and that's fine. I don't expect everybody to know the ins and outs of a gasoline engine. But the bottom line is this: octane rating refers to the fuel's ability to resist compression (heat). If an engine has a 87 octane spec, and you run 93 octane in it, and the computer "doesn't change a thing"...then what would result is that the engine would not run efficiently and it may even be hard to start in cold weather. If it truly never ever altered the spark timing, fuel pulse, VVT, etc. and the fuel octane changed, then you would end up having issues over time.

There HAS to be some compensation set up in the ECU to handle these situations. Some companies like Ford advertise two horsepower levels depending on fuel octane, other companies like FCA tell you to use 87 only for marketing (appearance of convenience) reasons, but in one way or the other all of them are programming their powertrain controls to "see" what type of fuel is in the tank.

 

[Lou Bunn]

A few years ago, my oldest daughter had an internship at Duke University and it meant about a 50 minute (avg) commute 1 way - now it included rural roads, city and freeway driving. The car was a Mazda 3, with a 2.5 and automatic. We measured the mpg from 2 gas stations - filled up on Saturday each time and the difference was 2 or more mpg difference. We did the same test twice to be sure.The winner was a few cents higher per gallon but they stated it was Top Tier Gasoline. I've been using name brand gas in everything ever since. Oh - and it was the regular 87 each time.

 

[Litfuse]

There's a lot of hatin' going on in this thread, and that's fine. I don't expect everybody to know the ins and outs of a gasoline engine. But the bottom line is this: octane rating refers to the fuel's ability to resist compression (heat). If an engine has a 87 octane spec, and you run 93 octane in it, and the computer "doesn't change a thing"...then what would result is that the engine would not run efficiently and it may even be hard to start in cold weather. If it truly never ever altered the spark timing, fuel pulse, VVT, etc. and the fuel octane changed, then you would end up having issues over time.

There HAS to be some compensation set up in the ECU to handle these situations. Some companies like Ford advertise two horsepower levels depending on fuel octane, other companies like FCA tell you to use 87 only for marketing (appearance of convenience) reasons, but in one way or the other all of them are programming their powertrain controls to "see" what type of fuel is in the tank.

The ECU can compensate for all qualities of fuel, to protect the motor. This doesn’t mean it will adjust to make more power, unless it was intended for a higher octane. Ford does list two different horsepower ratings, but this is for the ecoboost motors. The ecoboost motors also like e-85. I have a Ram 1500 with the 5.7 hemi and the manual recommends 89 octane. So FCA does recommend octane above 87 if it makes a difference.

 

[DesmoDog]

A few years ago, my oldest daughter had an internship at Duke University and it meant about a 50 minute (avg) commute 1 way - now it included rural roads, city and freeway driving. The car was a Mazda 3, with a 2.5 and automatic. We measured the mpg from 2 gas stations - filled up on Saturday each time and the difference was 2 or more mpg difference. We did the same test twice to be sure.The winner was a few cents higher per gallon but they stated it was Top Tier Gasoline. I've been using name brand gas in everything ever since. Oh - and it was the regular 87 each time.

The cheaper brand probably used more ethanol than the other.

 

[Markham]

With an older motor you would probably notice a difference.

 

[Majestic]

I have to believe if the higher octane was beneficial (mileage or power) Jeep would take advantage of that. I don't know all the ins and outs of federal mpg testing, but if there was scientific, measurable difference, Jeep would recommend the higher octane and claim the better mpg. Until then, I will continue to use 87 unless I hit the premium gas button by accident (which my other car recommends)(and other cars for the last 10 years).

Exactly. To squeeze out a couple more gallons to raise their fleet average, Jeep engineers went through the effort to make a 4 cal turbo engine with a huge lithium battery connected to a giant starter and required 91 octane, when duh....they should have just required 93 octane on the 3.6L.
Maybe slap a magnet on the fuel line while they’re at it.

 

[wrc777]

93 runs about $0.60 more than 87 here. Lately that is almost a 30% difference. It is a hard sell to pay that much extra. Some places seem to have ethanol free premium which probably does give better mileage than 10% ethanol 87 octane.

 

[robaw]

My $0.02 worth...
Where I live 88 octane ethanol blend is considerably cheaper than premium blends. Not enough of a benefit for the cost in my experience.

 

[smithrd65]

Unless your engine is knocking, buying higher octane gasoline is a waste of money. ... 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.
Paying a Premium for High Octane Gasoline? | Consumer Information
https://www.consumer.ftc.gov › articles

 

[misanthrope]

Unless your engine is knocking, buying higher octane gasoline is a waste of money. ... 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.
Paying a Premium for High Octane Gasoline? | Consumer Information
https://www.consumer.ftc.gov › articles

Stop it! Take yer words 'n' yer facts 'n' yer book-learnin' big citified Tesla-drivin' ways 'n' git! I've been drinkin' 91-93 octane on my Cheerios fer years and I'll tell yer, it's done helped me one whole heap of a lot. Yer just a'spreadin' that fake news I've been hearin' so much about.

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