Unleaded Gas type -2021 GMC Yukon Xl

[swathdiver]

I only put 87 in my 6.2 L Denali and the engine doesn't knock. Ever.

You have to be dumb to put premium gas in it. Prove it to me otherwise

You ain't gonna hear it. You can see it on a scan tool though.

Your knock sensors work.

Great, every time you accelerate and it starts a knockin' the timing gets pulled and then you go to pass a car, it starts to knock and the timing gets pulled again, 100 more times during that drive. Knocking all the way. Wouldn't it be better to not knock at all?

GM might consider adding a low octane table in the computer for cheapskates like Toyota and Dodge do, but I reckon GM figures their customers paid extra for the engine to enjoy its performance.

Any student of LS and LT history knows the toll 87 octane and cheap gas takes on an 6.2 engine over its lifetime. Seen plenty of busted pistons and rings on these forums and on youtube.

https://www.youtube.com/watch?v=wGABJCp03ko&t=649s

 

[Geotrash]

You ain't gonna hear it. You can see it on a scan tool though.



Great, every time you accelerate and it starts a knockin' the timing gets pulled and then you go to pass a car, it starts to knock and the timing gets pulled again, 100 more times during that drive. Knocking all the way. Wouldn't it be better to not knock at all?

GM might consider adding a low octane table in the computer for cheapskates like Toyota and Dodge do, but I reckon GM figures their customers paid extra for the engine to enjoy its performance.

Any student of LS and LT history knows the toll 87 octane and cheap gas takes on an 6.2 engine over its lifetime. Seen plenty of busted pistons and rings on these forums and on youtube.

https://www.youtube.com/watch?v=wGABJCp03ko&t=649s

100%. It's worth mentioning that the 2013 and earlier 6.2L engines have a 10.5:1 compression ratio. GM went to 11.5:1 in the L86 in 2014, which makes premium even more critical.

 

[Baja_Bob]

I myself, tend to stay away from the E85 type fuel. Ethanol can do damage to rubber and other materials over time, even if the engine is compatible I don't use it.

Filled up a tank on a rental Tahoe once before I returned it because it was cheap.

 

[R32driver]

I myself, tend to stay away from the E85 type fuel. Ethanol can do damage to rubber and other materials over time, even if the engine is compatible I don't use it.

Filled up a tank on a rental Tahoe once before I returned it because it was cheap.

Another reason not to purchase a former rental vehicle. Last year I bought a 2005 chevy kodiak with an 8.1L that was a former Uhaul truck and it's been an absolute nightmare

 

[MrBishop]

GM might consider adding a low octane table in the computer for cheapskates like Toyota and Dodge do, but I reckon GM figures their customers paid extra for the engine to enjoy its performance.

GM has high and lo octane tables. Spark is taken out quickly to prevent knock and returned at a slower, calibratable, rate. Tested at high and low altitudes and hot and cold, high and low humidity conditions. Local tuners create a custom cal that works in your area only.