Fuel grade

[JLMBT]

The 2022 and newer Yukon Denali, recommends 91 octane. Has anyone tested lower octane, and how that may or may not have affected the way the vehicle performs? Just wondering if you use 88 or 87, how will that affect the engine? Some folks have different ideas on this...I wanted to see what your thoughts were on this type of performance question...thanks for anyone that helps in your response.

 

[Doubeleive]

The 2022 and newer Yukon Denali, recommends 91 octane. Has anyone tested lower octane, and how that may or may not have affected the way the vehicle performs? Just wondering if you use 88 or 87, how will that affect the engine? Some folks have different ideas on this...I wanted to see what your thoughts were on this type of performance question...thanks for anyone that helps in your response.

it's a recommendation only, if it was any different it would say "required" that is the definition, no need to complicate it any more than that.
in furtherance it is simply a matter of lower octane "may" in some instance cause "engine knock" or pinging. driving it and consistently having engine knock could potentially cause internal engine damage over a extended period of time.
that is all period.

 

[Marky Dissod]

Recommended ... Not QUITE the same as required ...

Not nearly as well on 87 as it would on 91 octane, in terms of fuel economy, throttle response, performance measured against a stopwatch, and overall engine longevity.
The harder you drive, the better your engine will operate, the further the engine will go, and the longer your engine will last, with 91 octane.
The lazier easier you drive, the more you can get away with 87 octane - even then, 91 octane is ALWAYS better.

In the case of 6.2L V8s, using 87 for anything other than minimally demanding driving - one driver, no riders, unladen, unburdened, unhurried - may result in drivability symptoms that would not normally occur using 91 octane.

Whether or not you suffer symptoms using 87 that can be avoided with 91 depends as much on how it's being driven, as how well it's been maintained.

Just 'cause you can, doesn't mean you ever should.
I would NEVER tow / haul / drive 'hard' without using 91 octane in any 6.2L.

(My educated guess is that using 87 octane 'costs' anywhere 15 - 25 ft-lb of torque, regardless of RpM.)

 

[Joseph Garcia]

^^^x2^^^ Lots of opinions on this, but for me, I stick with the recommendations or better. It would be a shame to lose that wonderful motor. Also, if you choose to go with a lower octane gasoline, make sure that you use a top tier gasoline.

 

[Marky Dissod]

I don't consider my previous post an opinion.
That previous sentence is an opinion, however. Here's another one:
Using 87 octane when it says '91 octane recommended', in the long run, costs more than it appears to save.

 

[swathdiver]

The 2022 and newer Yukon Denali, recommends 91 octane. Has anyone tested lower octane, and how that may or may not have affected the way the vehicle performs? Just wondering if you use 88 or 87, how will that affect the engine? Some folks have different ideas on this...I wanted to see what your thoughts were on this type of performance question...thanks for anyone that helps in your response.

Using low octane fuel in a high performance, high compression engine results in constant knock and ignition retard which over time results in broken pistons and piston rings and of course, crummy performance. Generally speaking this knocking and pinging cannot always be heard because the trucks are so well insulated but can be seen with a scan tool. If it's good enough, it will even tell you which cylinders and how much.

 

[B-train]

I'm of a similar opinion, but my 2017 6.2L can run on 87 just fine. I'm not sure what's changed over the years. I think mine says 91 recommended as well. I've run 90K since I bought it on mostly 87 and it always runs fine. I have had a few instances where I've heard pinging, but it's seldom.

Also to note, these motors like ethanol fuel too. I've tried various blends of E85 and 87 to get a higher octane rating, as well as the cleaning properties of E85. Direct injection motors are more prone to carbon buildup, so that should help keep things cleaner. Mileage suffers a little depending on driving habors but it runs great.

 

[Stbentoak]

Recommended also means that if you chose not to follow the "recommendations" then GM does not have to extend you warranty if the problem you have can be traced to not following "recommendations."
IE: Using another weight oil than recommended, or putting "universal" coolant in your cooling system...

One of my wife's older vehicles would throw a CEL when you put 87 fuel in. Cleared up as soon as you put premium back in...

 

[Marky Dissod]

Using 87 octane fuel in a high performance, high compression engine results in constant knock and ignition retard ...

'constant' might be a lil bit of a stretch.
...
Any aftermarket tuner worth their weight in salt can write low octane tables for 6.2L V8s that will NEVER ping / knock ...
... so why did GM write low octane tables for 6.2L V8s that ping / knock unless you drive Miss Daisy?
I'd prefer 385 ft-lb & 375 horses knock-free, over 395 ft-lb & 385 horses that knock unless tailwind-driven downhill.

That said, consider this solution:
Add some E85.
If 2/3 of fuel in the tank is 87 octane gasoline, and 1/3 is E85, that tank of fuel is 91 octane.

 

[swathdiver]

'constant' might be a lil bit of a stretch.

Measure it with a scan tool and let me know.