2021 Tahoe High Country/93 octane or not?

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Ron McKuin

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In the real world, do you use 93 octane in the 6.2 or just regular 87? I know it is recommended, but do you do it?
Just bought a new 2021 Tahoe High Country and I don’t want to cause any harm to engine but 93 is 60 cents more per gallon where I live. Thanks and I hope this topic hasn’t been discussed to death!
 

Geotrash

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It's like smoking. You might get lucky, or you might not. Modern high compression engines use knock sensors to detect pre-ignition (pinging, in the old days), and retard the ignition timing to reduce it. But the system isn't perfect, and the engine will still experience transient internal cylinder pressures (ICPs) much higher than they would if being run on premium fuel - especially when used for towing or other high-output driving styles. Our engines use hypereutectic (high silicon) aluminum alloys for their pistons, which will accumulate fatigue over time. So when a high compression engine is run on lower octane fuel and experiences regular high ICP spikes, the pistons will eventually start showing signs of fatigue damage.

We have another member here who recently bought a used Denali with the 6.2 and has 3 cracked pistons, with one severe enough to require replacing the engine.
 
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I think the recommended octane is at least 91

I've always ran either 93 or E85, which is something like 105 octane.

A couple years ago when I was on a summer trip I was in the boonies and needed gas and the highest octane they had was 89. I did run it, but just that one tank.

Attachment is From my 2012 owners manual

Sent from my SM-G930V using Tapatalk
7171fb35558fadca31390e9b83047d1e.jpg
 
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Maybe a little crass in my response, but if you're worried about gas prices you should probably not have bought one of the largest consumer vehicles currently on the market. Cost me $90 to fill up yesterday, but that's the price you pay for a thirsty gal with a big tank (and a driver with a lead foot :D)
 

OR VietVet

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I can only assume that you bought what you researched, as you should do, and knew ahead of time that GM calls for high octane fuel.

I ran shops. I have seen the damage that detonation causes. Use the high octane for peace of mind. Make any riders chip in money for fuel.
 

wsteele

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I find the whole what gas is available locally and at what price very interesting.

Around here, I don't think I have seen 93 Octane (maybe Shell, not sure). Premium here is almost always 91 Octane, mid grade 89 Octane and Regular 87 Octane.

Also around here, almost universally, at least in the last year or so, the difference between Regular (87) and Premium (91) is rarely more than 10%.

On a recent trip down to Las Vegas on two lane highways through the Great Basin, most stations Regular was 85 Octane, Mid 87 Octane and Premium again 91 Octane. The delta between Regular and Premium was always about 15-20% up charge.

I assume the differences in what is available and what it costs is largely based on what the refineries locally are set up to produce and sell, but it sure doesn't seem like a very "efficient free market".
 

Fless

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The octane that is offered can depend on the elevation; higher elevation = lower octane. Our low here at a mile high is 85.
 

wsteele

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The octane that is offered can depend on the elevation; higher elevation = lower octane. Our low here at a mile high is 85.

Well that answers one of my questions, makes sense. On the route through the Great Basin, we were probably at like 6-7K MSL.
 

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