Interesting.

 

It may be why people are seeing a decrease in fuel efficency this summer. I haven't but I have been running 93 octane since June

 

Car is globally calibrated for 96 octane which is used in Europe... We get heavily retarded spark in summer and on low octane.. hence reduction in MPG

 

96 Octane in Europe is not the same as 96 Octane in the U.S. & Canada? In the U.K. the octane rating starts at 95?

MON is typically 8-10 points lower than the RON.
In the US/Canada and some other parts of the Americas, they use the average of the two. Hence lower.
In most other places, they just use the RON.
http://en.wikipedia.org/wiki/Octane_rating#Measurement_metho...

 

Yeah, could have guessed that... I get noticably better mileage when it's 70F with the A/C on than I do when it's 95F with the AC on...

Mike

 

...FYI, *all* EPA 50-state-certification tests are performed using 91 octane fuel, regardless of what the Owners Manual says.

...93 octane is used for non-CARB and non-50-state EPA tests.

 

This really applies to all vehicles, not just our Cruze. Although, it impacts on a lesser of scale on N/A engines.

Think about it. The hotter the air, the less dense the air, the easier it is for the A/F mixture to detonate and the less power made. Add a Turbo/SC, and it compounds that effect.

 

This really applies to all vehicles, not just our Cruze. Although, it impacts on a lesser of scale on N/A engines.

Think about it. The hotter the air, the less dense the air, the easier it is for the A/F mixture to detonate and the less power made. Add a Turbo/SC, and it compounds that effect.

Sort of...

If an engine has a low compression ratio and a set high-point for ignition advance that's in the 87 octane range, and almost never retards timing, then there's really nothing to gain from higher octane... The Trailblazer, for instance, gains absolutely nothing from anything over 87... It's because the compression ratio isn't really high, and the maximum advance on the timing is well within the 87 octane range...

The engine controls the fuel to go with the temperature/density of the air... It puts in less fuel when it needs less fuel...

Mike

 

Interesting. Mine is going in tomorrow for maintenance and to see if they can figure out why it has absolutely no power at times when hot. It has been 100+ here for 2 weeks and the car will barely get out of its own way. If the dealer can't find anything, I may run a few tanks of 91-92 to see how it works. I drive 3000+ miles a month and keep track of everything. I'll be able to tell pretty quickly if it works.

 

As for at potential energy from gasoline, BTU is 87 > 89 > 91 > 93. Ideally you would want a car to use 87 because it provides the most energy.

 

Yes but less of it can be used for the duration of the power stroke due to less timing advance.

 

my gas mileage has dropped ever since the weather went to the 90's and humid. just installed trifecta so we will see plus i have to use premium fuel anyway. My car was hesitating badly when hot and humid.

 

I only have 87, 89 or 93. I am not about to start mixing gas to get 91. 89 it is!

 

FINALLY!!!!!!!!!!!!!

We were seeing timing being pulled even in the early spring season with 87. 89 is pure minimum on the stock tune, 91 is even more ideal.

 

i'm using 87 no problems and exceeded the EPA mileage figures.

 

Do you have an Eco? If so that's pretty easy even if your MPG was suffering slightly.

 

Hot weather makes an incredible difference with this engine - far greater than my naturally aspirated truck. The A/C will also really hurt your mileage if you're not in recirculate mode.

I live in Houston and bought my car when the weather was still in the 50s and 60s. It's a major difference compared to now where it's 100. In fact it's a big difference between the 80's in morning and upper 90's in the afternoon. The biggest effect I've notice when the car's hot is that it feels like it has zero power until about 2000 rpm. In cool weather you can feel the power ramp up from much lower engine speeds.

At any rate though, this weekend I went to the beach, drove through 98 degree weather at 70-75 mph, and still got 39.5 mpg at the pump and 40.9 on the DIC.

 

:goodjob:

I have noticed with our weather being in the mid 80s and crappy every day my mpgs have nosedived.. I've gone for about averaging 42 a tank down to 37 without any changes in driving habits.

 

Ive been filling up at 91 since i got the car. Cleaner, better gas I say to myself lol.

 

one car I owned you were told in the owners manual to NOT use 91 as it could damage the engine.

 

116 it and forget it!

 

I only put 89 oct in my 85 vette so I sure as **** ain't putting 91 in this car!

 

Does your '85 Vette run 15PSI of boost?

Mike

 

Ok so is 89 or 93 better? I cannot get 91.

 

Ok so is 89 or 93 better? I cannot get 91.

93.

 

Will agree as here in Texas with 30 some odd days over 100 degrees, miliage has dropped almost 9 MPG. Looking forward to FALL !!!

 

If you know how awesome the car runs with trifecta installed you would have no problem putting 93 in!

 

I use 95 oct and can feel the pedal a bit smoother

 

...bring "back" the 115/145 octane military aviation gasoline (AVGAS), that'll let the timing be advanced...for sure!

 

Just add a water/methanol injection running about 50%/50% mix

 

...I looked through the article and seen they compared 2 different cars Cruze with 87 and the Regal with 91...enough said.

 

Apples-n-Oranges:

• the Cruze is turbo'd and spec'd for 87 octane.
• the Regal is turbo'd and spec'd for 91 octane.

 

Apples-n-Oranges:

• the Cruze is turbo'd and spec'd for 87 octane.
• the Regal is N/A and spec'd for 91 octane.

You sure they werent talkin the regal with the turbo?

 

Would you still use 89/93 octane in the fall/winter/spring? Around here it regularly gets below freezing in the winter.

Is the advantage still there in the colder months, or would it just be a waste of money?