6.2L gas issues

[AGT]

I use 87 octane 100% gas in my 5.3 and if I drive 60, I can get 19-20 hwy. In the city I average 16-17 being good. If I throttle it everywhere and not baby it I will get 14-16 avg.

 

I have homemade intake and magnaflow 14" muffler.

 

My 2012 denali OM on page 9-6 "Driving and operating section says the recomended octane gas is 87. I get around 16 mpg in this balmy mich 50 degree weather.

 

Just checked the owner's manual on your truck as well and this is, again, what I came up with........

 

"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."

 

I use 87 octane 100% gas in my 5.3 and if I drive 60, I can get 19-20 hwy. In the city I average 16-17 being good. If I throttle it everywhere and not baby it I will get 14-16 avg.

 

I have homemade intake and magnaflow 14" muffler.

 

5.3's have no need for premium fuel and aren't even been discussed here. 6.2 L9H's are.

 

 

Sorry just showing a comparison.

 

100% gas not 100 octane