Which octane do you use in your 1.4T Cruze? - Page 9
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View Poll Results: What octane gas in your 1.4T Cruze?

Voters
197. You may not vote on this poll
  • Regular unleaded (87 octane)

    67 34.01%
  • Mid-grade (89-90 octane)

    33 16.75%
  • Premium (91-93+ octane)

    97 49.24%
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Thread: Which octane do you use in your 1.4T Cruze?

  1. #81
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    Quote Originally Posted by rpcraft View Post
    Ok, I know this is a little late to the party but simply running a higher octane fuel will not boost your power output? It's actually used to control detonation (or knock if you prefer) from increased heat, which is a by product of increased power (i.e. an elevated boost or tune that will produce more power = heat). I don't want to get into the science of it here but if you care to read here is some fine information provided by the wonderful state of Minnesota:

    http://mn.gov/commerce/weights-and-m...ctaneFacts.pdf
    This has been discussed nearly to death here. Higher octane is more resistant to knock. The two main contributors to knock are combustion pressure and temperature. Both the 1.8 and 1.4Turbo engines in the North American Cruze run at high temperature for efficiency. The 1.4T adds higher compression as well to further increase efficiency and is part of the reason the LT, ECO, and LTZ all enjoy better fuel economy than the LS. In addition, for efficiency the Cruze's ECU uses very aggressive ignition timing. To reduce the impact of knock, the ECU backs off the ignition timing, but at the expense of engine power and efficiency. By running higher octane the ECU doesn't have to back off ignition timing as much, resulting in improved engine performance, power, and efficiency.

    In the real world (as opposed to the EPA testing facilities), the 1.4T engine benefits to the tune of 3-5 MPG by increasing octane from 87 to 91. The 1.8 engine also benefits, but to a lesser extent. Both engines provide more low end power with higher octane. The easiest way to determine if you need to run a higher octane is by paying attention to the throttle feedback. If it's pulsing, increase your octane. The pulse is the result of the ECU pulling timing to avoid knock.
    jandree22 and jdubb11 like this.

    2012 ECO MT - Black Granite/Cloth; 814 mile range; Bluetooth Stereo AUX; OEM Fogs w/Chrome Covers; GM Spare tire; VG Shark Fin
    2010 Mit Lancer GT MT (traded for ECO @31K miles)
    2002 Pont Montana AWD (traded for 2012 LS @182K miles)
    1990 Pont Transport (traded for Montana @240K miles)
    1986 Fiero GT MT (traded for Transport)
    1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)

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  3. #82
    ^^x2^^ i felt the pulsing in temps over 85 with the air conditioning on. ive been using 89 octane ever since and the pulsing has greatly been reduced/ is gone. havent, and probably wont try 91.


  4. #83
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    Title of this thread is:

    "Which octane do you use in your 1.4 (T?) Cruze?

    Pump says Top Tier 91 Octane Ethanol Free!

    What's coming out of that nozzle, I don't have the slightest idea.

    What I do know, whatever it is, getting 8 mpg less than what the calendar says the date is. January, I believe. Can't be the temperature difference, due to wind patterns, we have days in January that are actually warmer than days we had last June.

    But apparently the EPA says its winter, therefore its cold, so therefore, have to use winter gas.

    It did take them time to realize that when its cold, it does take a little more time to heat up the exhaust system components. A conventional O2 sensor is worthless until it warms up to about 350*F, thus came the open loop mode when the engine is first started. To accelerate the warm up time added a five cent nichrome heater to it. But where a typical 02 sensor retailed for around 30 bucks, the price skyrocketed to around 65 bucks.

    Same is true with the catalytic converter, worthless when cold, they wanted an electric heater added to that. But an engine is only 15% efficient and the alternator is only 50% efficient for an overall efficiency of 7.5%! To gain closer to 100% efficiency, we suggest adding ignition to the cat and spray gas directly into it. DOT would never hear of that, could result in an explosion due to fail ignition, so that project was dropped.

    Can you even imagine what an overpriced catalytic converter hanging under the vehicle exposed to road salt and other road hazards would cost the consumer?

    So instead, the EPA started playing with the gas, but not based on actual temperature, based on the calendar. So thus the rotten fuel economy we are getting, based on the calendar.

    Could waste your time and write to your congressman, I have better luck explaining this to my one year old grandson.

  5. #84
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    Quote Originally Posted by jdubb11 View Post
    ^^x2^^ i felt the pulsing in temps over 85 with the air conditioning on. ive been using 89 octane ever since and the pulsing has greatly been reduced/ is gone. havent, and probably wont try 91.
    If you're happy with 89, there is no reason to pay the additional cost of 91.
    jdubb11 likes this.

    2012 ECO MT - Black Granite/Cloth; 814 mile range; Bluetooth Stereo AUX; OEM Fogs w/Chrome Covers; GM Spare tire; VG Shark Fin
    2010 Mit Lancer GT MT (traded for ECO @31K miles)
    2002 Pont Montana AWD (traded for 2012 LS @182K miles)
    1990 Pont Transport (traded for Montana @240K miles)
    1986 Fiero GT MT (traded for Transport)
    1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)

  6. #85
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    I voted 87, but I have tried both 89, and 91/93 for a couple of tanks. Can't say I've noticed any difference in fuel mileage, performace or smoother running engine with any of them, but it is winter here in northern NY so maybe it will be different come summer. And at $6.00 more a fill up here, I think I'll stick with the 87.
    2012 Eco MT gone
    '13 Dodge Dart STX

  7. #86
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    Quote Originally Posted by mikep88 View Post
    I voted 87, but I have tried both 89, and 91/93 for a couple of tanks. Can't say I've noticed any difference in fuel mileage, performace or smoother running engine with any of them, but it is winter here in northern NY so maybe it will be different come summer. And at $6.00 more a fill up here, I think I'll stick with the 87.
    Good call. With the lower winter temps the intercooler isn't heat soaked, resulting in a slightly cooler compressed air flow from the turbo. When the temps start rising above 75-80F you may want to revisit your octane rating.
    jdubb11 likes this.

    2012 ECO MT - Black Granite/Cloth; 814 mile range; Bluetooth Stereo AUX; OEM Fogs w/Chrome Covers; GM Spare tire; VG Shark Fin
    2010 Mit Lancer GT MT (traded for ECO @31K miles)
    2002 Pont Montana AWD (traded for 2012 LS @182K miles)
    1990 Pont Transport (traded for Montana @240K miles)
    1986 Fiero GT MT (traded for Transport)
    1985 Fiero 2M4 MT (traded for Fiero GT @8K miles)

  8. #87
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    Quote Originally Posted by Quick10 View Post
    Where did they say you should run 89? I never got notified about that.
    I too have not seen anything about 89 octane. I have tried all of them, mostly from Shell. 91 gave me the worst mileage and I could not detect any power increase at all. I have been putting in the lowest cost, mostly 89 with 10%ethenal. Most stations here have reg 87 without ethenal and 89 with 10%ethenal. I have kept track of all but the last few weeks of fillups. The tanks without ethenal are just very slightly better mileage, but not worth the extra cost. My engine always runs strong and smooth no matter what gas I have put in it. I think the compter adjusts to what you put in it. One note on power: during the very hot days in summer, 95F and up, the power is somewhat less, especially with heat soak sitting in hot sun.

  9. #88
    1st Gear 20131pz69's Avatar
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    I run 91 octane. On my 2nd tank of 91, there was significantly less knock under regular driving and I can now shift up earlier without knock. Bottom line- I have increased mileage from the 91, the engine is safer due to less knock and will remain cleaner due to the increased amounts of detergent in the premium fuel. It may not be required, but it's financially sound ...

    Before evaluating a change in octane, I would run through 2 full tanks of 91 or reset the ECU (disconnect battery for 30? minutes) so the cruze can re- calibrate.
    Last edited by 20131pz69; 01-17-2013 at 01:58 PM.
    2013 Cyber Gray/ black 2LT 6M RS. stage 0 tune for 91 octane- vtuner

  10. #89
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    Quote Originally Posted by obermd View Post
    Your car will also start improving. It took almost 10,000 miles for my ECO MT to really find it's fuel economy legs.
    Wow, really? I'm not there yet, only around 7k miles (11k kms) in the dead of winter and I'm completely impressed by my car's fuel-miserness. Any more will just be icing on top of the icing on the cake.
    '12 ECO MT

  11. #90
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    Quote Originally Posted by titan2782 View Post
    1)Not when you're seeing 5-10 mpg gain.
    Care to share with the rest of us who is seeing 10 MPG gains? Going from 35 to 45 MPG is a 29% improvement, not likely on a fuel octane upgrade!

    The most extreme example I've seen mentioned is 5 MPG. Let's try to keep this reasonably factual...
    '12 ECO MT

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