6.2 engine in the Serria truck.

[Bikerjon]

8 hours ago, CASEY7777 said:

Tried 87 and 93 octane, not hauling heavy loads. I get the same gas mileage with 87 or 91 octane.

What year truck and what motor do you have?

[CASEY7777]

2020 Sierra Denali and 2011 Sierra SLT, both have 6.2 Litre engine.

[onewheat]

185k on my 2014 - always with Premium fuel.  16k on my '23 in the last 6 months - always Premium as well.

 

[swathdiver]

On 9/30/2023 at 9:08 AM, wenlund said:

Does anyone use regular gas in their truck, if so what effect does it have? 

After about 100K miles of running low octane fuel in the motor it is not uncommon to see broken rings and pistons.

 

You cannot hear knocking and pinging like we used to in the past, it can be seen on a scan tool though.

[Oilguy]

I have two trucks with 6.2L engines. One has 12K and the other has 38K. I have always run regular in both trucks and have no pinging and get 20-21 mpg on the highway. 

[swathdiver]

8 hours ago, Oilguy said:

I have two trucks with 6.2L engines. One has 12K and the other has 38K. I have always run regular in both trucks and have no pinging and get 20-21 mpg on the highway. 

You really cannot hear it, has to be seen with a scan tool.  At what altitude do you live?

[SporkLover]

Sorry but this is addressed in the owner's manual.  Page 299 for 2023 GMC Sierra. 

 

Quote

Premium unleaded gasoline meeting ASTM
specification D4814 with a posted octane
rating (R+M)/2 of 91 or greater is
recommended. If unavailable, unleaded
gasoline with a posted octane rating of
87 may be used, but will result in reduced
performance and driveability. If heavy
knocking is heard when using gasoline rated
at 91 or greater, the engine needs service.

 

Previous years noted that extended use may result in damage to the engine.  I will note that if you use low octane, and damage occurs from predetonation you can be sure they will use that against you for any power train warranty claims.  Excessive oil consumption resulting from excessive blowby from the piston rings?  Owners fault for using wrong octane and causing damage to pistons from predetonation.  Easy to see it too because these are hypereutectic pistons.  The likeliness of excessive damage like this is pretty low....but as noted you can be sure they will use it against you. 

[diyer2]

On 10/13/2023 at 6:33 AM, Oilguy said:

I have two trucks with 6.2L engines. One has 12K and the other has 38K. I have always run regular in both trucks and have no pinging and get 20-21 mpg on the highway. 

[Black02Silverado]

93 here and when I can I mix 40/60 E85 to 93.  Runs great and love the exhaust smell.

[Transient]

On 10/3/2023 at 11:24 AM, CASEY7777 said:

Tried 87 and 93 octane, not hauling heavy loads. I get the same gas mileage with 87 or 91 octane.

Edited October 20, 2023 by Transient

[oldmann]

If you can't hear the pinging of the 6.2 it isn't because it doesn't do it.  Your hearing is not good enough to detect it.  Both of mine have done it since day one at least a little on 89 and a lot on 87 octane.  

[Z45]

I have owned several (4) new Sierra Denali's with 6.2L engines since 2010 and use 91 octane. 93 is not available close by.   I once was forced (empty tank late at night) to use 89 because the Shell station was out of 91 and I could notice the loss (hesitation) of performance on hills.    Not one of these engines has given me any trouble, never use oil and I plan to keep it that way.   If you don't want to use premium, why buy a 6.2L engine, just get the V6.