6.2 vs 5.3 and premium gas

[tomgilk]

I'm only here to chip in that Premium fuel at Costco is just a few cents more than regular everywhere else. I filled up with premium this morning for $3.19 a gallon and most other stations are close to $4.

 

[PatDTN]

I'm only here to chip in that Premium fuel at Costco is just a few cents more than regular everywhere else. I filled up with premium this morning for $3.19 a gallon and most other stations are close to $4.

Ditto Sam's Club near Knoxville. Actually beats Costco by a couple of cents. I do feel a tiny seat of the pants difference in favor of Costco.

 

[swathdiver]

Ditto Sam's Club near Knoxville. Actually beats Costco by a couple of cents. I do feel a tiny seat of the pants difference in favor of Costco.

Costco is Top Tier and Sam's doesn't advertise it as such but could be depending on who they buy from at the time. Actually tried to buy some today but the lines were longer than I had patience for!

 

[Stbentoak]

Costco is cheap but always 16 cars deep. Not worth the wait….

 

[SSGUNNER]

Costco is cheap but always 16 cars deep. Not worth the wait….

It is when you got that auto stop/start.

 

[Z15]

Premium is recommended and there is a label on the filler door saying so as well as in the owners manual. They shy away from saying required because the ecm (computer) will try to adjust for the lower octane fuel by detuning the engine. But keep in mind although it may say 87/89 on the pump it could be less with no-name brands.

I purchased my first 6.2L in 2012 (Sierra Denali) after having recurring problems with 2008 Sierra 5.3L. I have on occasion been forced to use 87 or 89 because that pump was out of service at the time (broke or no fuel). In those instances I could feel the difference in performance because leaving my house in one direction I have a 5 mile up-hill grade and I noticed the hesitation with 87. While you may not hear anything these engines are affected LSPI (low-speed pre-ignition). See pic below on the results of LSPI.

I have NEVER regretted getting the 6.2L, matter of fact I won't even consider buying anything else. I have had (all new) Sierra Denali's, 2012. 2015, 2017, 2021. All I keep for exactly 3 yrs and traded and traded when GM offered employee pricing for everyone or 0%.

 

[petethepug]

Forgive me, iphone in one hand, cuppa coffee in other hand and just noticed I was in the outskirts of the 2021 forums vs 07-14 land. ...

I recognize the difference in low and top grade fuel here in CA mostly by the lack of the motor refusing to kick down going up hills. We’re 87, 89 & 91 octane. The difference in the 93 octane available in TX was a blast. The truck had been gone through for a complete pre-delivery inspection and in top tune. Instant power delivery.

By the time it got back to Cali the honeymoon was over until … was discovered locally. I was happy with a 25¢ savings from Costco. With e85 the 6.2 is a very happy camper at the expense of MPG. I get 5-12 mpg on e85 depending on my idle vs. Highway driving.

I realize this is about choice A or B but leaving out plan C or e85 based on 100+ octane is missed. A $2 to $2.5 a gal savings is a $50+ savings ea fill up. The discernible difference is the frequency in fill ups or a change from about 250/280 to 190/210 miles per tank.

It’s obviously a logistical thing if you can get , and get it on the cheap. I just can’t believe, for the moment at least, we get the 6.2’s full 405 hp and save over $2h a month on fuel cost. The savings is paying for the needed rear main seal, oil pan gasket & trans service since the Esky just hit 150k mi.

 

[a4edwin]

It is when you got that auto stop/start.

It’ll be the same after you have to replace the starter. At least that’s how I feel about that.

 

[SSGUNNER]

It’ll be the same after you have to replace the starter. At least that’s how I feel about that.

I actually went today to fill up, 20 min wait. Could of been worse. Only options were 87 or 91 so went with 91 at 3.99 a gallon.

Honestly, I don't really miss the 6.2 or regret opting for the 5.3 and feel its sufficient. Wont be racing off the line at the light or for passing and believe me the passing capability on the 5.3 is pretty good and not lacking anything. If I felt I needed a need for speed I'd have opted for the 392 wrangler or Jeep SRT. Even considered the 392 charger but those are due for a refresh soon and was coming from a jeep already so...Tahoe it is

 

[DollyDenali]

My wife’s previous vehicle needed premium… put in 87 and it would throw a CEL. Switch back to premium CEL went out…all I need to know….

Same happen to my '07 Escalade. Girlfriend put in 87 the 2nd time and it ruined my O2's and cat's

 

[waynehead99]

Honestly, I don't really miss the 6.2 or regret opting for the 5.3 and feel its sufficient. Wont be racing off the line at the light or for passing and believe me the passing capability on the 5.3 is pretty good and not lacking anything. If I felt I needed a need for speed I'd have opted for the 392 wrangler or Jeep SRT. Even considered the 392 charger but those are due for a refresh soon and was coming from a jeep already so...Tahoe it is

Agreed... the 5.3 for me is plenty. I didn't by this vehicle to take people off the line... I have other cars/motorcycles for that .

 

[gaffster01]

I should have data next week on this. Got the reader and app just haven’t had time to do anything. Will be good comparison as the truck has 91 octane in atm for pulling and will put 87 in after.

 

[wsteele]

Just a few data points driving my 5.3L flex and recording engine data with my Tech 2. With E10 87 (Costco), driving around town, my engine has knock sensors going off all the time with correlated timing adjustments. I have concluded this is how the engine is tuned, to "ride the knock sensors" for timing adjustments when running 87.

I haven't tried E10 91 yet, but I did run a tank of E85 through (it was actually 80% Ethanol, which has a very high octane rating relative to the E87-E91 range) and the knock sensors did still kick off once in a while, but much less.

I will try running the Costco E10 91 next and maybe post the two snapshots side by side for comparison, but I suspect the knock sensors will be more active with the 91 than they were with the E85.

It would be nice to have one of the guys who have a 6.2L and a Tech 2 post up similar results. I suspect even with 91, the engine will be riding the knock sensors some, if my results with the 5.3L is any indication. I definitely wouldn't ever consider running 87 in the higher compression 6.2L.

The caveat I would offer is my engine is high time, so likely is more prone to knock than a new engine with less build-ups, etc.

My opinion on the 6.2L and the additional cost of Premium is, I wish my engine was a 6.2L.

 

[Gibby13]

We had a 6.2 in our '11 Escalade and then a 5.3 in our '15. For our '21 Yukon XL Denali we went with the 6.2. The Suburban was a little bit of a turd.

Also we ran premium for the first 3000 miles or so in the '21 and then went with regular for 3000 miles. The MPG gain was around 14% but premium cost 35% more here. We run just cheap regular now as we always have before.


And from the manual you can run as low as 87.

 

[gooffeyguy]

We had a 6.2 in our '11 Escalade and then a 5.3 in our '15. For our '21 Yukon XL Denali we went with the 6.2. The Suburban was a little bit of a turd.

Also we ran premium for the first 3000 miles or so in the '21 and then went with regular for 3000 miles. The MPG gain was around 14% but premium cost 35% more here. We run just cheap regular now as we always have before.


And from the manual you can run as low as 87.

View attachment 349997

Yes, as the highlighted sentence says, it can be used. Then continue reading after the highlighted part

 

[wsteele]

We had a 6.2 in our '11 Escalade and then a 5.3 in our '15. For our '21 Yukon XL Denali we went with the 6.2. The Suburban was a little bit of a turd.

Also we ran premium for the first 3000 miles or so in the '21 and then went with regular for 3000 miles. The MPG gain was around 14% but premium cost 35% more here. We run just cheap regular now as we always have before.


And from the manual you can run as low as 87.

View attachment 349997

I would probably be using 87 as well if I planned on sending it back under the lemon law anyway.

 

[Gibby13]

I would probably be using 87 as well if I planned on sending it back under the lemon law anyway.

 

[swathdiver]

We had a 6.2 in our '11 Escalade and then a 5.3 in our '15. For our '21 Yukon XL Denali we went with the 6.2. The Suburban was a little bit of a turd.

Also we ran premium for the first 3000 miles or so in the '21 and then went with regular for 3000 miles. The MPG gain was around 14% but premium cost 35% more here. We run just cheap regular now as we always have before.


And from the manual you can run as low as 87.

View attachment 349997

And you too ought to buy a little OBDII adapter and get an app for your phone so you can "see" what you cannot hear, that the engine is knocking and pinging with that swill gasoline you're using.

 

[michome]

My 2021 Denali has 18560 miles on it now without any engine issues I have been reading about recently. It has only ever seen 91 to 93 octane and gets a can of berryman every second tank.
I change the oil every 6000 miles with mobile 1 or at 10% whatever is first. I have been lucky with my vehicles since buying a denali since 2008. The only TSB I ever did was my 2018 trans flush to get rid of the shudder. The compression is borderline high, 91 octane always but you could get by with 89 with no towing in my opinion. Spending 80 grand for a vehicle takes me out of price per gallon concerns.

 

[swathdiver]

Took the Sierra out for a 0-40 on straight pump gas. 93 octane at 0% alcohol content from Racetrac.