# What gas should I run?



## sciphi (Aug 26, 2011)

There's been a lot of debate and speculation about what gas to run in the Cruze, especially the 1.4 turbo engine. Here are my recommendations based on fuel economy, responsiveness, whether tuned or not, and what is the "cheapest" for overall fuel costs. 

1.8 Naturally Aspirated (no tune):
87 octane

1.4 Turbocharged (no tune):
1. Premium unleaded (91 or 93 octane)*
2. 87 octane*
* Some folks have seen a difference in fuel economy on an untuned engine running premium unleaded. To be sure of any fuel mileage increase, running the car on 3-4 tanks of gas is needed to be sure. I noticed a 3-4 mpg increase in my Eco. This was enough to make premium gas cheaper overall for me than regular gas. Your mileage may vary. 

1.8 or 1.4T (tune):
Premium unleaded (91 or 93 octane) - This is for the regular tunes without self-correction for octane levels. 
_
Ethanol:_ A lot of people say to find non-ethanol (E0) fuel. While E0 helps with fuel economy, it is not available in all areas. Around me, E0 is almost impossible to locate. Since that is the case, I choose to go with 93 octane E10 (10% ethanol) gas. 

Fuel system cleaners:
The Cruze should not need any fuel system cleaners if it uses name-brand gas from a busy gas station. If the car feels slow or lacks power, a fuel system cleaner "might" be in order. Don't buy any of the $2-3 dollar ones. Those are a very expensive bottle of kerosene, and will do nothing. The ones to buy are priced from $5-10 a bottle, and have chemicals called amines in them. The bottle's label should read: "contains amines". The more amines, the better the product will clean. The most readily available are Chevron Techron Concentrate (not the ProGuard) or Gumout Regane. Redline SI-1 or Amsoil P.I. are reputed to have higher concentrations of amines, and are more expensive. The best way to use these is to let them sit in the tank and fuel system as long as possible. So, put it in during a week when the car is seeing regular use, and try to not re-fuel until 1/4 tank. 

I hope this was informative.


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## 70AARCUDA (Nov 14, 2010)

Excellent post!


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## ErikBEggs (Aug 20, 2011)

Thanks for taking the time to write this article - sticky  ?



sciphi said:


> T
> 1.4 Turbocharged (no tune):
> 1. Premium unleaded (91 or 93 octane)*
> 2. 87 octane*
> * Some folks have seen a difference in fuel economy on an untuned engine running premium unleaded. To be sure of any fuel mileage increase, running the car on 3-4 tanks of gas is needed to be sure. I noticed a 3-4 mpg increase in my Eco. This was enough to make premium gas cheaper overall for me than regular gas. Your mileage may vary.


Unfortunately, this is not backed up by science at all. Every source I research says it has no *direct* effect on fuel consumption. The manual states 87 octane is _required_ meaning it is tuned for 87. These sources explore this topic:

Will a Higher Octane Level Increase a Car's Fuel Mileage? - CarsDirect
http://mn.gov/commerce/weights-and-measures/images/OctaneFacts.pdf
Fuel saving - a professional engineer's view

Where premium fuel really helps the engine is in extreme temperatures. The Cruze has an inefficient intercooler that is pretty easy to heat soak at temperatures approaching 100F. Premium fuel is harder to denote, thus reducing this effect. Details are found here



sciphi said:


> Fuel system cleaners:
> The Cruze should not need any fuel system cleaners if it uses name-brand gas from a busy gas station. If the car feels slow or lacks power, a fuel system cleaner "might" be in order.


Not sure if this is a waste of money. The dealer swears by this every time I take it in. I use Sunoco exclusively because it is the highest volume and most competitively priced retailer in my area and the car runs better than it does on Exxon (blah). Top tier... scam?


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## obermd (Mar 3, 2012)

Higher octane *will* improve your fuel economy if you are switching because the engine is knocking. When an engine knocks it's not getting a clean burn and you are losing power as a result. Switching to higher octane when you're not experiencing engine knock is simply wasting money.

I just rechecked my owners manual. It states the car is "equipped" to run on 87 octane. As other posters have pointed out in other threads, this simply means there are knock detectors in the Cruze to retard the injection and spark of fuel in the cylenders. Also, the same 1.4L engine without the Turbo is used in the Volt and the Volt manual says it "requires" 91 octane.


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## Jim Frye (Mar 16, 2011)

obermd said:


> I just rechecked my owners manual. It states the car is "equipped" to run on 87 octane. As other posters have pointed out in other threads, this simply means there are knock detectors in the Cruze to retard the injection and spark of fuel in the cylenders. Also, the same 1.4L engine without the Turbo is used in the Volt and the Volt manual says it "requires" 91 octane.


Yes, but the Volt motor has 10.5:1 compression ratio, while the Cruze is 9.5:1. The Volt likely needs the extra octane for knock resistance. And the Volt motor makes 84 hp, so there are some other differences too.


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## Record_player (Nov 16, 2011)

once the turbo kicks in the cruze comprssion ratio goes up to around 20:1 so 91 will make a difference.


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## sciphi (Aug 26, 2011)

That's why I said, "Your mileage may vary", when discussing the effects of premium on a non-tuned 1.4T engine. Some folks might notice a difference for their driving conditions, some might not. I noticed a difference, while others haven't. That's fine, we all drive differently. 

Of course, if your Cruze is tuned, run premium.


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## 70AARCUDA (Nov 14, 2010)

Jim Frye said:


> Yes, but the Volt motor has 10.5:1 compression ratio, while the Cruze is 9.5:1. *The Volt likely needs the extra octane for knock resistance*. And the Volt motor makes 84 hp, so there are some other differences too.


...see this April 2012 article in *Road & Track*: http://api.viglink.com/api/click?fo...p; TRACK</b>&jsonp=vglnk_jsonp_13314923000541

...and this _previous_ posting about this article:



70AARCUDA said:


> There's an article worth reading in the April 2012 issue of *ROAD & TRACK*, "*Premium Fuel Futures--A primer on high-test gasoline: Is it for you?*," pages 84-89, by Dennis Simanaitis (their resident engineering editor).
> 
> It's well worth reading. Here are some 'tid-bit' quotes to _pique_ your interest:
> 
> ...


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## danimal (Oct 4, 2011)

I'm on a road trip and I found 87 octane with 0% etOH or 93 octane and 10% etOH what would be better for fuel economy?


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## sciphi (Aug 26, 2011)

What engine and what are the temperatures and elevations? I'd lean toward the 93 octane myself seeing how the turbo is working harder at elevation. If the temperatures are up around late spring/early summer, I'd definitely go with the 93 octane.


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## danimal (Oct 4, 2011)

1.4 6mt eco. We are in Iowa headed back to Colorado and the temp is in the low 60's traveling at night. Obviously going up in elevation to about 5000 when back to colo. 


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## obermd (Mar 3, 2012)

danimal - run at least mid-grade when you get back to Colorado. I switched my Cruze ECO MT from 85 to 87 on my last tank. I have 450 miles on this tank and the DIC is reporting 47.3 mpg. My previous high DIC reading after three quarters of a tank used was 44.7 mpg. I plan to run a couple of more tanks of 87 before going to 89 to see if that also improves my mpg. 87 appears to have eliminated my engine knocking.

I don't know if mid-grade will help at lower altitudes, but it definitely helps at altitude.


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## danimal (Oct 4, 2011)

I live in colo and run 91 since day one. So far on the trip out 783 miles on 18.5 gals so 42.3 calculated running 65-70 with a wicked cross wind through nebraska (3 adults a baby and full trunk also) I saw the 87 with no EtOH and 93 with 10% EtOH and wondered which would be better


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## UlyssesSG (Apr 5, 2011)

danimal said:


> I live in colo and ... saw the 87 with no EtOH and 93 with 10% EtOH and wondered which would be better?


_*Hi Danimal,*_

This is a no-brainer as far as I'm concerned: *GO! with the good stuff *which in your case is the 87 octane fuel without ethanol. It'll pack more punch per gallon than the adulterated E10 and E15 blends. I wish we had the option of choosing in my neck of the woods, but we don't.

Miles of smiles and happy, carefree motoring my friend! I know I'm loving my Cruze more and more with each passing day.

*UlyssesSG*


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## Stingray1974 (Mar 14, 2012)

My 2015 Cruze runs well on premium. If I run regular it gets 10% less mileage and has little power. With premium it has less knock which lets the ECU automatically adjust timing and turbo for more power which means less gas needed. More horsepower out of same engine means less gas pedal to do the same work.


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## Alex V. (Sep 20, 2013)

I've never run multiple tanks of regular in a row to gauge fuel economy because, based on my performance loss the few times I've chosen 87, I don't care if the extra 10-15 cents a gallon isn't made back in fuel economy, I want it to run its best. I have, however, experimented with 89 with and without ethanol, E-free 91, and numerous brands of ethanol 91 and 93, and don't find the performance or economy improvement detectable. My car has pulled above-rated fuel economy often enough on 89 that I think that fuel is adequate in stock form. (All observations have been made between 700 and 1,100 ft. in altitude on an untuned 1.4T/M6 LT.) I've added a can of Seafoam to the fuel every 10,000 miles with satisfactory results, but after the previous posts I'll keep an eye out for the other products.


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