What Octane should be used?

[Modded]

The best synthetic is still Mobil 1 Extended Performance haha, screw RP.
If running high octane gas makes one feel good, then go ahead and do it and feel good. But it really does not make a difference as long as it is a good gas station, so I will keep running my 87 and be happy.
I bet if gas prices were to randomly hit $4.20 for regular, some of you guys (that use it when the car/tune does not call for it) will revert back to using regular, not premium.

 

[wheatswake]

The best synthetic is still Mobil 1 Extended Performance haha, screw RP.
If running high octane gas makes one feel good, then go ahead and do it and feel good. But it really does not make a difference as long as it is a good gas station, so I will keep running my 87 and be happy.
I bet if gas prices were to randomly hit $4.20 for regular, some of you guys (that use it when the car/tune does not call for it) will revert back to using regular, not premium. [/QUO

how did you come to the random number of $4.20?

 

[stevek]

how did you come to the random number of $4.20?

A few summers ago it was that high...

Most jet skis and boats called for premium. On the lake it was over $6/gal(stupid tax for filling on the water) and on the land it was nearly $5 a gallon. $4.90 x 16 gal (per ski) x 2 skis > $150

The boat is another story... it's not mpg, it's gph - gallons per hour

EDIT: This is all of Nevada... http://www.GasBuddy.com/gb_retail_p...=Nevada&city2=&city3=&crude=n&tme=36&units=us

I am talking about up in the mountains where it's a $.25 extra per gallon than in Reno. Then to fill with premium...

 

[phileaglesfan]

If an engine is designed to run on 91 then that is the way to go. On one designed to run with 87 it is a waste. I know the 6.2 requires premium on my Denali and in my Vette. I believe both owner's manual said performance will be reduced. I know both get less mpg with cheap gas.

However the higher you go the less of a factor octane has on power. Our base octane in Utah is 85, top is 91.

I'll usually use Chevron or Texaco in my cars. I have a credit card with them and get $.10 a gal back for this year. It is amazing how premium costs $.20 more a gallon at one station, then $.30 more at the next station (both Chevrons). Even with the 31 gal tank on my Denali XL it is about $6-9 a tank which isn't much since you are talking about 500-600 miles on the highway.

 

[2007TahoeLTZ]

You would need a higher octaine if you were to get a Black Bear tune or another chip.

I did not know this. So if I got the Black Bear tune that everyone seems to suggest, I'd have to use 91?

 

[stevek]

I did not know this. So if I got the Black Bear tune that everyone seems to suggest, I'd have to use 91?

Well, tune it with what you'll use in it.

 

[Z15]

from my owners manual 2010 GMC

Gasoline
Use of the recommended fuel is an important part of
the proper maintenance of this vehicle. To help keep
the engine clean and maintain optimum vehicle
performance, we recommend the use of gasoline
advertised as TOP TIER Detergent Gasoline.
Look for the TOP TIER label on the fuel pump to ensure
gasoline meets enhanced detergency standards
developed by auto companies. A list of marketers
providing TOP TIER Detergent Gasoline can be found
at www.toptiergas.com.


Gasoline Octane
For all vehicles except those with the 6.2L V8 engine
(VIN Code 2), 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.

If the vehicle has the 6.2L V8 engine (VIN Code 2), use
premium unleaded gasoline with a posted octane rating
of 91 or higher. You can also use regular unleaded
gasoline rated at 87 octane or higher, but the vehicle's
acceleration could be slightly reduced, and a slight
audible knocking noise, commonly referred to as spark
knock, might be heard. If the octane is less than 87, you
might notice a heavy knocking noise when you drive.
If this occurs, use a gasoline rated at 87 octane or
higher as soon as possible. Otherwise, you could
damage the engine. If heavy knocking is heard when
using gasoline rated at 87 octane or higher, the engine
needs service.

from 2009 CTS owners manual

Gasoline Octane
If the vehicle has the 3.6L V6 engine (VIN Code V), use
regular unleaded gasoline with a posted octane rating
of 87 or higher. If the octane rating is less than 87, you
might notice an audible knocking noise when you drive,
commonly referred to as spark knock. If this occurs, use a
gasoline rated at 87 octane or higher as soon as possible.
If you are using gasoline rated at 87 octane or higher and
you hear heavy knocking, the engine needs service.
If the vehicle has the 3.6L V6 engine (VIN Code 7), use
regular unleaded gasoline with a posted octane rating
of 87 or higher. For best performance or trailer towing,
you could choose to use middle grade 89 octane
unleaded gasoline. If the octane rating is less than 87,
you might notice an audible knocking noise when you
drive, commonly referred to as spark knock. If this occurs,
use a gasoline rated at 87 octane or higher as soon as
possible. If you are using gasoline rated at 87 octane or
higher and you hear heavy knocking, the engine needs
service.

If the vehicle has the 6.2L supercharged V8 engine
(VIN Code P), use premium unleaded gasoline with
a posted octane rating of 91 or higher. For best
performance, use premium unleaded gasoline with a
posted octane rating of 93. In an emergency, you can use
regular unleaded gasoline with an octane rating of 87 or
higher. If 87 octane fuel is used, do not perform any
aggressive driving maneuvers such as wide open throttle
applications. You might also hear audible spark knock
during acceleration. Refill the tank with premium fuel as
soon as possible to avoid damaging the engine. If you are
using gasoline rated at 91 octane or higher and you hear
heavy knocking, the engine needs service.

 

[sparky5309]

If you have an older engine - say 70K+, you may notice an increase in performance with a higher octane gas. The reason is because the carbon deposits on your piston heads will ignite more fuel of a higher octane then the lower octane - so you also might see better MPG - but this ISN'T an indication that you need to run higher octane fuel - it means you're pistons are carboned up and they need to be cleaned. Then when you go back to 87, it'll run like it did with 91. A newer engine will ignite 87 just as well as 91. running premium with a newer engine is just throwing money out the tail pipe. Some say that if you continually run premium, that equals less carbon build-up over time, but I would argue that the money spent over that amount of time would be more expensive then just getting your pistons cleaned when they need it.

 

[mikeumkc]

the escalade's engine is higher compression. it requires 91+ octane.

the 5.3s are lower compression, and only require 87+.