Sold on 89 Octane

[Nokones]

I used to use 87 in my Jeep with the 3.6 and decided to try out 91 last year. Since then I've stuck with the 91, but I've got to say: I've seen no difference in gas mileage, power, or "smoothness". In fact earlier today I noted that it still makes that sound like ice and rocks in a blender when I cold start it LOL.

What brand gasoline?

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[TheRaven]

The engine needs 89 octane.

Curious as to the data that brought you to this conclusion - the people who designed the engine disagree.

I do not believe you'll see much if any fuel economy differences in the 3.6L, but the difference in power is especially noticeable on hot days.

I, and many others, have seen zero power difference running 87 octane. We have also seen zero gain in fuel efficiency. Note that the factory HP and torque ratings were established on its recommended fuel grade (87). So essentially you are claiming that you see higher than rated HP on higher octane fuel...which is not somethin that's been found to be typical.

Don't assume that your experience is the same as others, nor that your experience is the most common.

 

[Nokones]

There was report put out recently that listed the various brands of gasoline to stay away from if you want better performance and longevity and to minimize youf maintence/repair operating expense and emission related issues. These brands were noted in that report: Circle K, Costco, Safeway, Sunoco non-race fuels, Speedway, Amoco. There were a total of 16 brands listed. I can't remember the rest of them.

I personally use only Chevron 89 with no problems, at least non detected so far on my 33 Wrangler Rubi 2 Dr 3.6L with only 6500 miles.

A few years ago, I had to have my Dually Diesel emission tested and the inspector commented to me that he can tell that I use Chevron Diesel Fuel because of how the tail pipe looked. He said only vehicles that use Chevron Diesel fuel will leave a tail pipe clean.

The Techron additive really does work.

 

[Windshieldfarmer]

Curious as to the data that brought you to this conclusion - the people who designed the engine disagree.



I, and many others, have seen zero power difference running 87 octane. We have also seen zero gain in fuel efficiency. Note that the factory HP and torque ratings were established on its recommended fuel grade (87). So essentially you are claiming that you see higher than rated HP on higher octane fuel...which is not somethin that's been found to be typical.

Don't assume that your experience is the same as others, nor that your experience is the most common.

My experience is more or less the same the as your’s though I do run 91 during hot weather, pulling loads, or highway driving. I believe in those types of conditions there is value added n minimizing the potential for pre detonation. That said I cannot quantify any mileage improvement and perceived power increase might just be a placebo affect. I do try to use top tier fuels. I have the 2.0.

 

[TheRaven]

My experience is more or less the same the as your’s though I do run 91 during hot weather, pulling loads, or highway driving. I believe in those types of conditions there is value added n minimizing the potential for pre detonation. That said I cannot quantify any mileage improvement and perceived power increase might just be a placebo affect. I do try to use top tier fuels. I have the 2.0.

Personally, with the 2.0, I would run premium. There is a lot more variation in effective compression ratio in forced induction motors than in NA motors. While the computer CAN compensate just like it does on the 3.6, this particular application is across my personal comfort line. Secondarily, you will generally see a loss of power and fuel efficiency when running 87 octane on an FI motor. I have not tested this myself on the 2.0 in the Wrangler nor even the 2.0 in my CTS, but it's what I would expect if I did.

 

[pablo_max3045]

I don't really see the point of using a fuel that is a higher octane that what is specified by the engineers who designed the engine.
Sure, it won't hurt anything, but since the engine is tuned for a lower octane you also won't see any benefit.
I would say that using an octane rating lower than specified is what's going to bork your engine over time. Not to mention, using a lower octane can void your warranty.

 

[jadmt]

There was report put out recently that listed the various brands of gasoline to stay away from if you want better performance and longevity and to minimize youf maintence/repair operating expense and emission related issues. These brands were noted in that report: Circle K, Costco, Safeway, Sunoco non-race fuels, Speedway, Amoco. There were a total of 16 brands listed. I can't remember the rest of them.

I personally use only Chevron 89 with no problems, at least non detected so far on my 33 Wrangler Rubi 2 Dr 3.6L with only 6500 miles.

A few years ago, I had to have my Dually Diesel emission tested and the inspector commented to me that he can tell that I use Chevron Diesel Fuel because of how the tail pipe looked. He said only vehicles that use Chevron Diesel fuel will leave a tail pipe clean.

The Techron additive really does work.

Costcos west of Mandan has the best gas available. It is supplied by Cenex which has the highest standards of any gas company. My good buddy worked at the Bulk plant that mixed all companies gas and said Cenex had the highest standards. he said Cenex was absolute sticklers on standards. as far as Octane he said Cenex will always test higher than what is on the pump.

 

[Skeethree]

Yep. Our 2.0's can accept 87 octane, but they pull timing to save themselves. Like you, I'd rather provide the extra octane in the fuel and allow the engine to make maximum power. I've only run premium 91 or 92 (highest we can get here) since I bought it new.

Far as I know, the 3.6's are designed to run on 87 (full power). They might quiet down a little bit with some higher octane but it doesn't seem to provide much more power like engines designed to run it.

I've only used 87 in my 2 door 2.0. No pinging, no weird behavior. Only 1200 miles so far but first tank average was 24 mpg and second was 26. Generally driving 35-60 MPH at elevation between 1000 and 1500 feet. Driving mixed about half local and half 20-80 mile drives. I feel like the EPA is robbing Jeep rating the 2.0 at 20 MPG.

 

[watchluvr4ever1116]

Over $1 per gallon more for premium vs regular here, with no improvement in fuel economy or power. I‘m sticking with regular in my 2.0.

 

[morrisl29]

About this time last year I switched my Chevy Colorado 3.5 IF 10.5:1 compression off of 87 octan and started using 89. I noticed an improvement in responsiveness and idle. I recently bought a jeep 3.6 V6. 11:1 compression. The dealership in Denver filled the tank with 87. I left and drove back to Dodge City, KS. After crossing into KS. I stopped and put about 15 gallons of 89. In about 10 miles the fuel milage stated going up. Going from 19.1 to 22.9 over the next 125 miles. The terrain from Denver to Dodge is fairly similar, mostly rolling hills. Not a scientific testing method, but reasonably good anecdotal evidence. Both Chevrolet and Jeep say 87 octane is good enough for these engines. But I'm old school so I believe that with the compression ratios at 10.5:1 and 11:1 the higher the octane more timing that can be used. The more Timing the more efficient an engine will run. Equaling more power and better fuel milage. Even though the ECM prevents pinning (by retarding the timing) pinging must still happen for the ECM to know timing must be retarded. Pinging is not good for an engine. So pings prevent is damage averted. In short I believe the added expense of higher octane fuel saves problems if your playing the long game.

 

[dstevens]

The 'off brand' stations buy on the open market so you likely get the same gas as a brand station. Only difference might be the top tier stations who add more detergent. Use of detergent debatable on DI engines anyhow.

Knock can be detected by the ECU well before pinging occurs, and the timing adjusted accordingly. Basically it is a pressure wave that increases in amplitude as you get closer to knock.

 

[Windshieldfarmer]

About this time last year I switched my Chevy Colorado 3.5 IF 10.5:1 compression off of 87 octan and started using 89. I noticed an improvement in responsiveness and idle. I recently bought a jeep 3.6 V6. 11:1 compression. The dealership in Denver filled the tank with 87. I left and drove back to Dodge City, KS. After crossing into KS. I stopped and put about 15 gallons of 89. In about 10 miles the fuel milage stated going up. Going from 19.1 to 22.9 over the next 125 miles. The terrain from Denver to Dodge is fairly similar, mostly rolling hills. Not a scientific testing method, but reasonably good anecdotal evidence. Both Chevrolet and Jeep say 87 octane is good enough for these engines. But I'm old school so I believe that with the compression ratios at 10.5:1 and 11:1 the higher the octane more timing that can be used. The more Timing the more efficient an engine will run. Equaling more power and better fuel milage. Even though the ECM prevents pinning (by retarding the timing) pinging must still happen for the ECM to know timing must be retarded. Pinging is not good for an engine. So pings prevent is damage averted. In short I believe the added expense of higher octane fuel saves problems if your playing the long game.

Perhaps higher octane played a role in your improved mileage but I suspect elevation change, wind, and speed factored more. Candidly there is no way a 2 point octane boost alone would increase your gas mileage by nearly 20%.

 

[Willys41]

I used to use 87 in my Jeep with the 3.6 and decided to try out 91 last year. Since then I've stuck with the 91, but I've got to say: I've seen no difference in gas mileage, power, or "smoothness". In fact earlier today I noted that it still makes that sound like ice and rocks in a blender when I cold start it LOL.

Kyanche. Just for your information.
The rattle the you are hearing on cold starts is from the valve train.
I had the same issue on both my 2020 willys and 2018 Rubicon 3.6.
What is happening is the oil filter housing and oil cooler is draining back to the oil pan after sitting over night.
When I did my first oil change on my willys I was thinking this is going to be a mess changing the filter put I was supersized to find NO oil in the housing and no oil dripping off the filter.
The solution was the Baxter oil filter adapter.
It has a check valve and the screw on filter also has a anti drain back valve
Worked for me. No more bone chilling rattle rattle on startups.

 

[OlGray]

Going from 87 to 89 made a big difference for my 2 door, 3.6 auto. The timing ping went from “you could hear it well” to “nearly nothing at all”. My wife used to ask what that noise is all the time. I haven’t heard that question since moving to 89. It’s even better with ethanol free 91. We don’t have ethanol free 89 around here that I know of. And yes, there is a difference in performance for this particular engine. Maybe not yours, but this one, yes. That little engine will turn over those 37s on dry pavement with factory 4:10s on 89 octane, WITH ethanol. That’s not a common practice but I had to get out of someone’s way and I think I found the radiator with the pedal that day. I was shocked as all git out. You could a probably seen that grin from outer space. Only a .75 mpg increase, but the engine is like a different engine with 89 in it. I didn’t think it would make that much difference if any. After reading some post out here I decided to give it a try. I think I’m on my third or fourth tank of 89 and that’s probably what I’ll put in it from now on.

 

[AcesandEights]

20% increase in mpg based on octane? I call BS. If that were the case all car mfg would spec 89-octane to beat EPA requirements.

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