Chevrolet Cruze Forums banner
Cancel
Create thread New Garage Forums

Fuel Grade

Tags
fuel grade
Jump to Latest

What fuel Grade do you use

  • 87

    Votes: 78 76%

  • 89

    Votes: 12 12%

  • 91

    Votes: 6 5.8%

  • 93

    Votes: 7 6.8%
  • Total voters
    103
21 - 40 of 77 Posts
Discussion starter · #22 ·
Skilz10179 said:
If the car is tuned for 87 then you should run 87, period. Higher octane fuel is only going to waste your money if the car is tuned for 87. Higher octane fuels are used to prevent detonation, often referred to as knock. Detonation is when cylinder temperature or pressure is high enough to cause combustion before the spark plug fires. The higher the octane rating the the more resistant the fuel is to detonation. The car's ECU uses a knock sensor to sense detonation, when it sees knock it will retard ignition timing to lower cylinder temps also causing a drop in hp.

Long story short, if the motor is tuned for 87 from the factory it shouldn't be detonating on 87 octane fuel and using higher octane is only going to waste money...
Click to expand...
This is exactly what I point out in the first post. Most engines than run regular have a compression ratio under 9 or 8, anything higher than 9 also usually warrants higher grade fuel. the 1.4LT engines have a 9.5:1 compression ratio.

Even if the engine is capable of running on 87 due to tuning, the same tuning will account for the higher octane fuel and advance the timing. I just don't think 87 on a 9:1+ compression ratio engine is a smart idea. But thats my opinion
 
#24 ·
SilverCruzer said:
Can this be verified? Yes the ratio matches higher octane, but how do you know for sure that after being tuned for 87, is it still OK to run higher octane?
Click to expand...
Here's the problem, GM will not give you a straight answer as to exactly which fuel you SHOULD run. They've told me in an email that you CAN run 87 or 89. Now why would they suggest 2 different fuels?

Now we also know that the Cruze has a knock sensor to help prevent detonation and will pull timing to do so - pulling timing=less power. Why would they have such a sensor and ability if 87 was fine?

And again with the 9.5 compression ratio, any other engine I've seen is running 89 or usually higher with 9+.

3 valid reason why I'm sticking with 89. Not to mention it also feels different to my butt dyno :/
 
#25 · (Edited)
1) the Knock Sensors are what *tell* the ECM there's too much advance, just as like the Lambda (O2) Sensors are what tell the ECM what the exhaust A/F-ratio is.

2) on a normally aspirated (NA) engine, the knock sensors allow the engine to use maximum advance permittable for the grade of gasoline being used, because the actual grade can vary quite a bit (87±3) depending upon location, season, and blending.

3) on a "charged" engine (super- or turbo- or both), the knock sensors allow the engine to use maximum manifold pressure for the grade of gasoline being used; again, using detection of spark knock as the limiting criteria.

4) depending upon how 'smart' the ECM algorithms are (and if wide-range sensors are used), just about ANY grade gasoline can be used, because if its octane is too low, the ECM simply retards timing and dumps manifold pressure. If higher octane is detected, the ECM simply uses more timing and more manifold pressure.
 
Save
Reply Quote Like Like
#26 ·
RS LTZ said:
This is exactly what I point out in the first post. Most engines than run regular have a compression ratio under 9 or 8, anything higher than 9 also usually warrants higher grade fuel. the 1.4LT engines have a 9.5:1 compression ratio.

Even if the engine is capable of running on 87 due to tuning, the same tuning will account for the higher octane fuel and advance the timing. I just don't think 87 on a 9:1+ compression ratio engine is a smart idea. But thats my opinion
Click to expand...
Pretty much every n/a motor built today running on 87 octane has a higher than 9:1 compression. The chevy cobalt that the cruze replaced used a 2.2L ecotec as it's base engine that has 10:1 compression and runs on 87 octane. Over the years there have been many advances like combustion chamber design, aluminium heads and blocks, direct injection, tuning, ext that have made engines more efficient than ever on lower octane fuel.
 
#27 ·
Someone with access to tuning / data logging software needs to do some logging on 87 to really find out if its causing knock and ignition retard. Until someone can prove otherwise, i'm sticking to 87 like everything I've read from GM suggests is used...
 
#29 ·
Nothing but 89 or better here. They run mid grade for regular price 3 days a week here, so it's a no brainer. Eco is averaging 40+mpg @ 70mph. Can't argue with that!
 
Save
Reply Quote Like Like
#30 ·
DarylB said:
Nothing but 89 or better here. They run mid grade for regular price 3 days a week here, so it's a no brainer. Eco is averaging 40+mpg @ 70mph. Can't argue with that!
Click to expand...
If its not going to cost you any more money then why not! :)

I asked Vince at Trifecta Performance about this since i knew they had some experiance data logging on the 1.4 but he could not give me any real information. I don't think they spent much time logging on 87, instead i'm sure they focused all their efforts for maxium output on premium pump gas. This is a direct quote from him...

"The factory calls for 87 octane. Economy and performance may be slightly better with higher octane fuels, but I don't have any data to support that assertion."
 
#31 ·
...for once I won't be the Devils' Advocate and agree 100% with Vince's statement.

...and, I'll add: "...lack of supporting data doesn't necessarily mean something isn't true...only that it's not (yet) verified true or false."
 
Save
Reply Quote Like Like
#34 · (Edited by Moderator)
The only thing you may notice with a higher octane fuel is that your car could possibly run a little quieter. Your mileage shouldn't increase and neither should your performance... With that being said, if spending the extra $.10 per gallon makes you feel better about it, go for it. I do in my motorcycle. It has a compression ratio of 10.0:1 which could run okay at 89 octane, but I always run premium anyway.

The other thing that comes into account is variable valve timing on the intake side equals variable compression ratio.

Read this for more good info.
 
#36 · (Edited)
...quoting from page 9-39 of our 2011 Chevrolet Cruze Owner Manual:

"Recommended Fuel
​
Use regular unleaded gasoline with a posted octane rating of 87 or higher. If the octane rating is less than 87, an audible knocking noise, commonly referred to as spark knock, might be heard when driving. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. If heavy knocking is heard when using gasoline rated at 87 octane or higher, the engine needs service."​

...notice carefully that last paragraph:


"If heavy knocking is heard when using gasoline rated at 87 octane or higher, the engine needs service."

...it does not say, "...use a higher octane grade fuel..." it says "...the engine needs service."

...you can use higher octane grade fuel, but it's not necessary!
 
Save
Reply Quote Like Like
#37 ·
Octane and Top Tier Gasoline

While octane level is always interesting to discuss, long term benefits are likely gained by using Top Tier Gasoline. The EPA reduced detergent requirements in gasoline a while ago as some bad stuff was showing up in potable water linked to additives. Not sure exactly how this played out at EPA, however, reduced detergents result in more engine deposits. Check out Top Tier Gas on a google search. It may be possible that paying a few pennies more per gallon for top tier gas is better than paying for higher octane, if you have to choose one or the other. BTW, gas is already over $8.00/US Gallon in the UK and over $5.00/US gallon for premium grade in Canada. OMG!
 
#40 ·
thats funny... dont they go by the pint or something up in Canada?
My nephew lives up there.. and he was talkin bout $1.something a pint.. some time ago. lol
that confused the heck out of me... XD
 
Save
Reply Quote Like Like
21 - 40 of 77 Posts
About this Discussion
76 Replies
28 Participants
Last post:
Mrk9182
Chevrolet Cruze Forums
posts
760K
members
118K
Since
2010
CruzeTalk.com forum, news, discussions and the best community for owners to discuss all things related to the Chevy Cruze.
Full Forum Listing
Explore Our Forums
General Discussion Gen1 1.4L Turbo Gen1 Service Issues đź‘‹ CruzeTalk New Member Introductions Gen1 Audio, Electronics & Electrical