# Using 91 octane- I may have found something.....



## Eddy Cruze (Jan 10, 2014)

I doubt you're on to anything significant?


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## neile300c (Jul 8, 2014)

I am under the impression that all Dexos oil is now full synthetic. What's interesting, is I have not found any gas with no ethanol that is top tier, only gas with up to 10% ethanol. I'm guessing the additives are what makes it top tier. Not sure about the octane. One of the reasons I bought another Cruze was the fuel economy and cost saving. Going to a higher octane will not save me as much money, especially with it 40 cents more than 87. I will do it if it makes since, but it will be frustrated.


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## ethangsmith (May 7, 2017)

Doing digging on old threads, this has popped up before on 1st gen 1.4L engines. Consensus then was to use 91 and ignore the owner's manual. The RPO codes are unique to the car, the owner's manual isn't. Looks like this practice has continued on to the 2nd gen 1.4L as well.


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## Premier17 (May 20, 2017)

Personally I think it's crazy to run anything but premium in any force induction car. IMO, Marketing and bean counters put in the 87 octane rating in the manual to help sell it as an economy car. I've seen better performance, and better gas mileage with premium and I'll stick with that.


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## ethangsmith (May 7, 2017)

I'm going to run this tank of 89 octane out and then start with premium only. One of the stations near me even has ethanol free 91!


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## obermd (Mar 3, 2012)

Is KRD printed on the label in the glovebox? It was on the Gen 1s, even the 1.8L LS model.


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## ethangsmith (May 7, 2017)

I didn't look to see if there was a label in my glovebox. I don't recall seeing one, so I'll have to look around. If they still have RPO labels, I would think it's on there somewhere.....


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## jblackburn (Apr 14, 2012)

You can tell that the engine is noticeably more happy on premium.

Not sure if the pistons blowing apart is a cause of the fuel, or oil, or tune or may be some of each. At the end of the day, what GM kinda needs to do is just richen up the fuel mixture to run regular like the Ford Ecoboost engines and stop chasing after the loftiest MPG goals in their respective classes. Just like the first generation, no one's going to want to buy an economy car knowing that it needs to run Premium fuel, and piston failures aren't helping their case for turbo engines being as reliable as naturally aspirated engines that some competitors are still using.

It was the Malibu 1.5T that had the recall/reprogram/oil change done, btw. Impala uses a regular 2.5 NA or 3.6 NA and doesn't really care what you put in the tank.


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## ethangsmith (May 7, 2017)

You're right. I did say Impala. It's the Malibu with the 1.5T recall for the reprogram and oil change. Sorry about that.


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## Merc6 (Jun 8, 2013)

What they said above. Before we get into the "why 91/93 is a waste" video soon to be posted, the video showed a Cruze running 87 for it's entire life then put to the test of 93 while in DFCO state. If Gen 2 is like Gen 1 you can't just toss 91/93 in and be good especially when the video doesn't show the car in a regular or stressed load at all. The car needs to run the 87 out completely after a few tanks to hold the 91 (KRD) map.


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