89 oct. no ethanol vs. 91 oct.

[appzattak]

Would anyone know how much of a difference there is between the 2? Could 89 oct be used on a 91 tune?

Trying to see what way I want to go. Currently I run 89 no ethanol. I've been running it since the first tank I got from the dealer went empty. (currently have 2,500 miles on my truck). I pay 2.63 a gallon for the 89 no ethanol, but if I go to 91 no ethanol it is like 3.63 a gallon! Or I can just run the standard 91 for about 2.81 a gallon.

Just wondering if at this point the non ethanol is worth it and if 89 is close enough to run on a 91 tune???





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[MADDOG]

89 is marginal on a 91 tune. You could hurt the performance as the tune is looking for higher octane fuel and it isn't there and you may end up seeing a lot of knock.

Run the standard 91 instead. If you are concerned about corrosion in the fuel system due to the ethanol, add a corrosion inhibitor once in a while when you fill up.

 

[appzattak]

89 is marginal on a 91 tune. You could hurt the performance as the tune is looking for higher octane fuel and it isn't there and you may end up seeing a lot of knock.

Run the standard 91 instead. If you are concerned about corrosion in the fuel system due to the ethanol, add a corrosion inhibitor once in a while when you fill up.

I was thinking the same, that 1.00 a gallon jump for the 91 non ethanol is steep...like 85 bucks to fill up....

Thanks!



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[Burla]

I tell you there is a huge difference between costco 91 and the 87, and I always add PEA cleaner lube s1-1. Last case I bought off amazon was like 8 dollars and change per bottle and that is good for 2 tanks. Anyhow, back to the gas I love how this thing runs on 91, stock tune. Incredibly responsive compared to sluggish with 87. I kind of hate it too, because I am cheap and I would rather use 87, but I can't do it.

 

[Trooper2]

So Burla your saying you put Costco 91 in your truck?

 

[West27]

I run Costco 91 up here in Idaho and don’t have any issues with my custom 91 tune. Now if I am going to race it or pull something I won’t run it with the 91 tune and will get gas somewhere else. But for everyday driving I think it is fine and cheaper.

 

[appzattak]

I run Costco 91 up here in Idaho and don’t have any issues with my custom 91 tune. Now if I am going to race it or pull something I won’t run it with the 91 tune and will get gas somewhere else. But for everyday driving I think it is fine and cheaper.

where in Idaho?


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[West27]

Boise

 

[appzattak]

Boise

Awesome! I'm down in Jerome.


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[Addicted2fishing]

I have used Costco 91 since day one. It’s the same price as regular and nearby gas stations so it’s a no brainer. Is Costco gas bad or something ?


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[West27]

I have used Costco 91 since day one. It’s the same price as regular and nearby gas stations so it’s a no brainer. Is Costco gas bad or something ?


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I think you will get many different opinions on here but here is my thought and experience. Costco gets top tier gas so really the only thing that could be different between Costco and say shell is the additives they add. I have datalog many different gases with my truck to see which one will show less st knock under WOT and I couldn’t really tell a difference between any and also non ethanol gas.

The biggest thing I have found that will increase st knock is the intake air temp and the temp of the engine if it is heat soaked or not. I run a good fuel injection clean and lubricant about every other month and always run 91 octane. If I am going to take it to the track and if it is hot out I usually run some torco octane booster to help with the st. If I am towing heavy then I will run 91 but run my 89 tune just to be safe.

Again this is just my opinion and other people may not agree but my truck is no race truck and 98% it is just a daily driver so Costco gas saves me month so I can put that savings to more performance parts or other toys.

 

[Addicted2fishing]

I think you will get many different opinions on here but here is my thought and experience. Costco gets top tier gas so really the only thing that could be different between Costco and say shell is the additives they add. I have datalog many different gases with my truck to see which one will show less st knock under WOT and I couldn’t really tell a difference between any and also non ethanol gas.

The biggest thing I have found that will increase st knock is the intake air temp and the temp of the engine if it is heat soaked or not. I run a good fuel injection clean and lubricant about every other month and always run 91 octane. If I am going to take it to the track and if it is hot out I usually run some torco octane booster to help with the st. If I am towing heavy then I will run 91 but run my 89 tune just to be safe.

Again this is just my opinion and other people may not agree but my truck is no race truck and 98% it is just a daily driver so Costco gas saves me month so I can put that savings to more performance parts or other toys.

Thanks for the reply! Much appreciated. I noticed the “Hemi tick” on mine when I first got it and the months leading up to the first oil change (3 months maybe?). I since switched to 91 and my oil change was the synthetic they use at dealer and so far no tick ! I should have been more thorough and payed attention to see if it was the oil or gas LOL. The reason I use Costco is it’s the same price as regular at esso or shell for 91 octane. I know I’m not gonna gain performance and not really expecting better MPG but I am happy that I’m not running ethanol in my truck for the same price as 87. If I had to use normal gas station I’ll surely be using 89 ha ha ha.

Thanks again for the response


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