New 2023 Yukon At4 Order - 6.2L unavailable

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RAMurphy

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That’s awesome! I work for Sikorsky and have built some of the newer K models (King Stallion). Great aircraft’s
Retired back in 2006, so I never got to fly the "K". I actually picked up a brand new MH-53E from Sikorsky so many years ago when we transitioned from the RH-53D to the MH-53E. It had that new car smell in the cockpit. Hard to believe the Navy is now retiring that aircraft. Wow, time flies...
 

WalleyeMikeIII

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Hm, its bad, in Russia we uses premium in both of them 5,3 and 6,2.... We think that using regular finished in tahoe 900))
What is your Octane rating on Regular and Premium there...that could be the difference.

In U.S., the 'Octane' rating posted on the pump is actually the AKI (Anti Knock Index), which is the average of Motor Octane Number and Research Octane Number...so AKI = (RON + MON)/2

GM specifies 87 AKI minimum for the 5.3 and 91 AKI minimum for the 6.2 in USA.

Here is a good description of the various Octane Rating Methods used/posted in Europe vs. USA. Note, I don't agree w/ the sentiments in the article that lower Octane Fuel is Lower Quality...it is simply less resistant to detonation under compression than higher octane fuel...whether this matters in a given application is dependent on engine design...but the article does get to how different countries use the different test methods.

 

Vladimir2306

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What is your Octane rating on Regular and Premium there...that could be the difference.

In U.S., the 'Octane' rating posted on the pump is actually the AKI (Anti Knock Index), which is the average of Motor Octane Number and Research Octane Number...so AKI = (RON + MON)/2

GM specifies 87 AKI minimum for the 5.3 and 91 AKI minimum for the 6.2 in USA.

Here is a good description of the various Octane Rating Methods used/posted in Europe vs. USA. Note, I don't agree w/ the sentiments in the article that lower Octane Fuel is Lower Quality...it is simply less resistant to detonation under compression than higher octane fuel...whether this matters in a given application is dependent on engine design...but the article does get to how different countries use the different test methods.

We have gasoline with an octane rating of 95. We pour it into both 5,3 and 6,2 engines
 

WalleyeMikeIII

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We have gasoline with an octane rating of 95. We pour it into both 5,3 and 6,2 engines
So your 95 is probably RON, which is like 91 US.
Your 98 is like 93 US.

95 probably overkill for the 5.3, but not sure what else you have available, nor what the cost is...5.3 in US model can run on US 87, which is your 91, but possible GM gave a different tune for your market?

Here is a good table:
 

Vladimir2306

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So your 95 is probably RON, which is like 91 US.
Your 98 is like 93 US.

95 probably overkill for the 5.3, but not sure what else you have available, nor what the cost is...5.3 in US model can run on US 87, which is your 91, but possible GM gave a different tune for your market?

Here is a good table:
We have gasoline with octane ratings of 92, 95, 98 and 100. In general, we have an opinion to be guided by the compression ratio of the engine: if more than 10,5, then gasoline is 95, if less than 10,5, gasoline is 92. The Tahoe 900, which has a 5.3 engine, had a compression slip of 9.9, so it drove perfectly on 92 gasoline. And the Tahoe T1 with a 5.3 engine has a compression ratio of 11, which means gasoline is 95. The Tahoe with a 6 2 engine has a compression ratio of 11.5. So also gasoline 95. But turbomotors are 98 gasoline, and for sports cars it is gasoline with an octane number of 100
 

WalleyeMikeIII

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We have gasoline with octane ratings of 92, 95, 98 and 100. In general, we have an opinion to be guided by the compression ratio of the engine: if more than 10,5, then gasoline is 95, if less than 10,5, gasoline is 92. The Tahoe 900, which has a 5.3 engine, had a compression slip of 9.9, so it drove perfectly on 92 gasoline. And the Tahoe T1 with a 5.3 engine has a compression ratio of 11, which means gasoline is 95. The Tahoe with a 6 2 engine has a compression ratio of 11.5. So also gasoline 95. But turbomotors are 98 gasoline, and for sports cars it is gasoline with an octane number of 100
Interesting that on the 5.3L V8, GM recommends 87 Octane in US, even w/ the 11.0:1 Compression ratio..owners manual excerpt..
1692737338484.png

What does your owner's manual say?

Regardless, running your 95, you certainly won't hurt anything in your 5.3, there is only positive to be had running the higher octane...but it may not be required and you may not see any benefit.
 

petethepug

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As of now, GM offers only the 6SP when mated to the 5.3L. Part of the desirability of the 6.2L is that 10 SP trans.

The 6.2L doesn’t have to lift a finger to get the truck moving. Once moving it doesn’t work as hard using lower RPM based on gearing, hp & torque. The byproduct is also longevity.
 

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