# Which gas to use? The manual says regular...but there’s a turbo?



## james18cruze (Jul 17, 2019)

The 2018 Cruze has the 1.4 turbo engine right? I know that the 1st gen required premium. Does the new one require it or is it just recommended?


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## snowwy66 (Nov 5, 2017)

The owners manual states 87 octane.

Every car and motorcycle I've ever driven. Has stated that. And the oldest car I've ever had was a '67 olds.

Unleaded gas didn't come out till 75. Leaded gas was phased out in the mid 90's.


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## obermd (Mar 3, 2012)

The Gen1 Cruze's engine was actually designed for 91 octane. GM Powertrain's software engineers worked with the hardware guys to monitor the engine for predetonation and changed the ignition maps when it was detected. The adjusted ignition map threw away anywhere from 5 to 10% of the power to protect the engine on 87 octane.

The Gen 2 engine was designed for 87 octane from the ground up. While 89 or 91 may help I'm going to give the same advice I've been giving since 2012.

Go run your tank down until the refuel light comes on. Then run two tanks of 89 in the car. If you notice a difference then repeat with 91 octane. After the testing, you need to determine which octane meets your driving needs and whether or not you're willing to pay extra for the higher octane.


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## snowwy66 (Nov 5, 2017)

I don't know about all the engine mapping.

But the debate pops up from time to time in the motorcycle forum.

My motorcycle is a low compression engine. 8.3. Therefore it makes no sense to run 91.
It's also stated that high octane is a slower burn. Increased compression would increase the burn rate. Or something like that. Been awhile since the discussion was brought up.

It also has something to do with elevation.
You easterners have high octane gas's over us westerners. We range 85 to 91 while you all range 87 to 93.

The cruze motor is 9.5. So it's kind of in the middle. 
I see some newer harleys coming out with 11 motors now. 93 is probably highly recommended.


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## ChevyGuy (Dec 13, 2014)

obermd said:


> While 89 or 91 may help I'm going to give the same advice I've been giving since 2012.
> 
> Go run your tank down until the refuel light comes on. Then run two tanks of 89 in the car. If you notice a difference then repeat with 91 octane. After the testing, you need to determine which octane meets your driving needs and whether or not you're willing to pay extra for the higher octane.


This test should be done during the hottest days. That's where you'll most likely encounter the difference. If the car is sluggish when the weather is hot, then there's a good chance that upping the octane will help.


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## Taxman (Aug 10, 2017)

snowwy66 said:


> The cruze motor is 9.5. So it's kind of in the middle.
> I see some newer harleys coming out with 11 motors now. 93 is probably highly recommended.


Is 9.5:1 the LUV engine?
OP is James18Cruze, which implies he has a 2018 with LE2, and IIRC that one's 10:1, plus more than an atmosphere of boost. Even with charge air intercooling that's got to be worse than 14:1 in a NA GDI engine.

From what I've heard, when you start the car, it assumes the highest (92? 93?) octane fuel/ignition profile, and then steps down until detonation goes away. So clearly it performs better on 93 octane, the question is whether you'll ever notice. What's also clear is that if your 87 octane costs $2.70 and 93 costs $3.30, any increase in MPG from 93 octane will not pay for itself, you have to be willing to pay for smoother performance and improved LSPI safety.


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## snowwy66 (Nov 5, 2017)

Gen2 gas motors all have same 153 horses. 19 model rated same as 16 model.

Compression ratio is the same.

I think I saw somewhere it was 9.5.
10 don't sound right.

But I could be wrong


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## Farmerboy (Sep 2, 2012)




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## jblackburn (Apr 14, 2012)

My Gen 2 (a 2016, so an early variant of it) runs 239487329742987987x better on 93 than 87. There's WAY more power down low in the rev range, it's less hesitant to get up and move, and it gets better gas mileage. When run on 87/89, there are some very disconcerting hiccups in acceleration that leave you going 'that doesn't feel right'.

GM continually tweaked the tune and spark plug requirement for the Gen 1 every year they made the car in hopes of making the things run better on 87 octane. They got it as good as they were going to get it by the 2015 model year.

I have not driven a 2018/19 Gen 2, but that has been my experience with 2 2016's and a 2017 rental I had.


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## Chad20101 (Jul 23, 2019)

james18cruze said:


> The 2018 Cruze has the 1.4 turbo engine right? I know that the 1st gen required premium. Does the new one require it or is it just recommended?


You can thats what Gm tested the cars with (RON 91)


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## califlady2018 (Jul 20, 2018)

james18cruze said:


> The 2018 Cruze has the 1.4 turbo engine right? I know that the 1st gen required premium. Does the new one require it or is it just recommended?


I have a 2011 Cruze bought it brand new and always have used 87 octane. My owners manual said I could use it. I have 122,450 miles and never had any problems


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## ChevyGuy (Dec 13, 2014)

califlady2018 said:


> I have a 2011 Cruze bought it brand new and always have used 87 octane. My owners manual said I could use it. I have 122,450 miles and never had any problems


How hot does it get in your area, and how does the car perform when it gets that hot?


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## califlady2018 (Jul 20, 2018)

I live west of the high desert in Southern California. So the summer are hot and dry. Sometimes it gets around 95 to 100. Last year we got to 110. One thing I forgot to put on my post is for the gas the manual does says you can use 87 octane but for the car to run better make sure the gas station is a Top Tier station. I been using Arco which out cheapest gas station and it is a Top Tier.


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## obermd (Mar 3, 2012)

Chad20101 said:


> You can thats what Gm tested the cars with (RON 91)


The EPA's test fuel is a 91 octane (MON + RON)/2. It's not generally available for retail sale, however. Once this testing is done then the powertrain engineers adjust for the "targeted" octane, again (MON + RON)/2 and then for the vehicle's weight and drag coefficients to get the advertised city/highway numbers. The combined is City * 0.65 + Highway * 0.35.


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## obermd (Mar 3, 2012)

califlady2018 said:


> I live west of the high desert in Southern California. So the summer are hot and dry. Sometimes it gets around 95 to 100. Last year we got to 110. One thing I forgot to put on my post is for the gas the manual does says you can use 87 octane but for the car to run better make sure the gas station is a Top Tier station. I been using Arco which out cheapest gas station and it is a Top Tier.


Switch to at least 89 octane in the heat.


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## snowwy66 (Nov 5, 2017)

87 has always been the number. In every vehicle I've ever owned. My oldest being a 67 olds. Unleaded and cats didn't exist then. My newest being a 17 cruze.

Even all my motorcycles.


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