Premium vs Regular = Spark Knock

[hosseface]

FWIW:

6k on the clock - 2015 6.2 Denali.

Using regular fuel since day 1. Just noticed a pretty heavy amount of spark knock / pinging that has happened since the weather cooled off.

One tank of premium through it and cleaned it right back up.

 

[KWIKNVA]

Wow, Does your owners manual recommend regular? I know mine 09' says 6.2L require 91 octane or higher. I do recall seeing a sticker inside my fuel door saying the same. See below

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, 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 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 you might
notice a slight audible knocking noise, commonly referred
to as spark knock. If the octane is less than 87, you
might notice a heavy knocking noise when you drive

 

[Lyon]

That's good to know. I'm planning on simply running Premium all the time; the difference in fuel cost is negligible especially if using the higher octane fuel has an objective benefit.

 

[ezdaar]

One step colder on your plugs will help as well

 

[Reels]

Just ran my second full tank through. First tank the dealer put in was 87 Octane. Second was 91. Definitely more pep with the 91 and average MPG is about 10% better.

 

[Lyon]

Great reasons to run Premium.

 

[ccapehartusarmyINF.(ret)]

you should only run premium if the manufacterer specifys premium
higher octane gas is for engines typically with a compression ratio above 11:1
91 octane has a higher flash point
so you can run premium in a engine that calls for regular just fine its just pointless and waste of money
but you should not run regular in a motor that requires premium you will get detonation

 

[Lyon]

IIRC the 6.2 has an 11.5:1 ratio and the 5.3 is 11:1.

 

[ccapehartusarmyINF.(ret)]

there yah have it

 

[hosseface]

1/4 tank of the premium completely got rid of the spark knock FWIW.