2017 Escalade/Denali L86 "requires" 93 octane - your experience?

[RobH]

The 2017 Denali and Escalade Owners Manuals say

"Fuel (L86 6.2L V8 Engine). Use premium 93 octane unleaded gasoline in your vehicle. Unleaded gasoline with an octane rating as low as 87 may be used, but it will reduce performance and fuel economy."

I know that the engine computer can enrichen the mixture and dial back the spark advance to prevent knock with lower octane fuel. And that most driving is with moderate to low load with these engines anyway which reduces pre-ignition/knock.

My perception is that, yes, 93 octane has more energy per gallon and more knock resistance than 87 octane, but not enough more energy and gas mileage to justify the price premium.

Since I don't plan to operate the engine above 3,000 RPM or at higher loads practically ever, will running 87 octane pose a problem?

If I buy the 2017 with the L86 with 37,000 miles,
I would get the transmission fluid flushed, and,
A tune with the AFM delete, which means the engine would be running at lower manifold pressure in V8 mode with eight cylinders working than it does in V4 mode with four cylinders working. I've seen that on my ScanGauge II with my 2016 L83 by running in M5 which disables the AFM.

What are your thoughts and experience on less than 93 octane?

 

[B-train]

Mine says 87 is fine, but premium is recommended, not required. I think I've heard some spark knock a couple times in 100k, but it really runs fine on 87. I've trailered with it (2 Honda Foremans, some firewood, and a full load of gear).

I'd say if you are concerned, then use premium. I've only really ever used 87 in my 2008 as well. Currently I blend about 20% E85 with 87 to get an octane rating of about 93 (again, 2008 denali). It absolutely loves it, and the mileage isn't much different than on 87.

I've run a blend in my 2017 as well. No check engine lights or weird running. It actually really liked it for the first tank I did on a trip. (About 20% blend). I just don't drive it enough to get a daily driver record of it. But, with the miles my wife puts on with 87, we've never had an issue.

I think based on what I gather from your driving habits, you'll be just fine.

 

[B-train]

One thing I forgot to mention is that fuel octane requirements can be affected by elevation. Being that you are probably closer to sea level than the midwest and mountain states, it may have an effect.

I've never had to run premium on trips to coastal areas, but something to keep on mind. The opposite holds true in higher elevations where lower octane actually helps vehicles run better due to less available oxygen to combust.

 

[Marky Dissod]

Best answer I can possibly give:
depends on how you drive.
The more gently you drive, the more you can get away with using 87.
I said 'get away with'. That runs kinda parallel to what GM said:
"Use premium 93 octane unleaded gasoline in your vehicle."
"Unleaded gasoline with an octane rating as low as 87 may be used,
but it will reduce performance and fuel economy."

The harder your L86 plays, or works, the more strongly 91 or 93 octane is recommended.
If you ever tow or race or drive with verve, or haul lots of people and/or stuff, 91 or 93 octane.

Part II coming ...

 

[Marky Dissod]

Since you are getting your ecm tuned:
be sure to inform your tuner that you'll prefer 87,
except when your engine must work or play hard.

Every pcm and ecm since '99 has had 2 separate spark tables - High Octane & Low Octane.
To oversimplify, if your tuner reduces timing in the Low Octane table by 2 degrees -
or something along those lines -
that would make it even safer to use 87, than GM originally intended.

Also, a question?: Can the L86 make use of E85?
If it can, you'll lose some range, but you'll gain octane / knock resistance.

 

[Joseph Garcia]

I've never seen 93 octane specified in an owners manual as the preferred fuel to use, but apparently it does exist (I saw lots of 91 octane specified as the preferred fuel). So, I learn something new every day.

The 6.2 LS was designed to be a high performance/racing engine, and it was later adapted for use in high end large SUV trucks to give them something other than the 'heavy and slow' feel. For me, 91 or 93 octane fuel is most compatible with the design of the 6.2, and I had Black Bear Performance give me a tune that is based strictly on 93 octane fuel. Sure, it is a more expensive fuel to use, but if I was only interested in low net fuel costs, I'd leave my 07 Yukon XL Denali in the garage and only use my Honda Fit. Of course, everyone has their own priorities, and that is cool.

Can you safely use 87 octane fuel in the 6.2? Some very knowledgeable and respected folks above have indicated that this can be safely done, and I fully trust these folks. Hopefully, @RobH you now have some great answers to your question.

 

[Geotrash]

I have a different opinion on this. Lots of reports out there on the interwebz of broken pistons and damaged ring lands from running 87 in the 6.2L. The I Do Cars channel on Youtube has some spectacular 6.2L failures from running 87 under high power operation such as towing uphill. You might get away with it for a while, but you pays your money, and you takes your chances.

 

[mwswarrior]

I have a '19 Tahoe Premier with the 6.2. I have 130K miles on her and she's been on regular unleaded most of those miles. I will typically use premium when I'm road tripping for the slight increase in performance and mileage. I wouldn't get either of these running around town so it's just not worth the extra cost over the years. I have had ZERO problems with anything in the engine or anything that could be attributed to the 87 octane. Service it properly and don't flog her at every stoplight and you should be good with 87 octane. Your results may vary...

 

[Eighthtry]

I agree with M Stuart. I and The Queen have a 2011 Yukon Denali XL with 208,000 miles on her. No problem with transmission ever or with the cylinder killer ever. It runs as brand new, including max RPMs in passing situations.

About 98% of my mileage has been with 87. No knocks that I ever heard, and that is something I am familiar with and can easily hear.

2% with 92 on trips that require a sizable amount of two lane passing. I started 92 in all travel for the first time at 190.000 miles It upped power considerably. I was fiat-footed surprised with that change. I had no idea it made that much difference. It still gets 87 around town.

This 208,000 miles is with no oil consumption, as in zero.

The Queen said new one, so she now has a 2023 Yukon Denali XL. It will be on the road for a few years. About to leave for a 30 day 4,000+ mile trip.

The 2011 is for sale if anyone is interested. It is in excellent condition, which includes the interior. The Queen maintains the car's looks. I am responsible for maintenance and repairs.

I suspect we will need to follow site rules for that.

 

[91RS]

I can guarantee anyone running 87 octane has spark knock that they either cannot hear because they don’t know what it sounds like or the ECM is pulling the timing so much to mitigate the knock and the cost of power. Why buy the 6.2L if $5-$10 extra per fill up to keep your engine safe is an issue? Just buy a 5.3L.

 

[Marky Dissod]

I can guarantee anyone running 87 octane has spark knock that either:
they cannot hear because they don’t know what it sounds like,
or the ECM is pulling the timing so much to mitigate the knock at the cost of power.

Sounds like another way of saying, GM did not write the L92 / L9H / L94 Low Octane table properly?
GM did say that one should be able to use 87 with lowered expectations.

Why buy the 6.2L, if $5-$10 extra per fill up to keep your engine safe is an issue? Just buy a 5.3L.

If GM offered a less-prestigious '6.0L that tows & hauls just fine on 87' option,
I bet a lot of people would take GM up on that offer.
I guess I get why Cadillac won't offer an 87 octane 6.0L, but GMC should.

Regardless, the solution is a tune where the Low Octane table is written with 87 in mind.

 

[91RS]

You can’t write a fuel table that works perfectly in all areas of the country, in different weather conditions, with different fuel additives. Once again, if the little difference in the price of fuel is that big of deal, don’t buy the high line vehicle. An engine costs $12k, why would you risk cracking the pistons over $10 per fill up?

The ** version of the 6.0L that came in the GMT-800 Denali, Escalade, and H2 required mid grade, if I remember correctly. The 6.0L that came in the 2500’s and vans up to a few years ago was designed for work and not high performance and only needed 87. The 6.6L gas engine only needs 87 also but again, designed for work not performance.

 

[petethepug]

A lot of the e85 crowd around here install alcohol sensors in the fuel line then and run a mix of Reg 87 & e85 until they get 95 octane.

The goal is 95 octane petrol based fuel for a racing tune, but the unintended effect is a blend of less expensive regular and even less expensive e85 or .. cheap racing fuel

 

[Marky Dissod]

designed for work not performance

This phrase makes me throw up in my mouth.
'Work' weighs more than 'Performance'? 'Work' uses less throttle than 'Performance'

If GM wanted to, they could write the 6.2L tables PROPERLY, lower the advertised peak ratings a bit, and have far fewer broken Gen4 6.2L engines.
Guess it makes the 6.2L look more like a prestige item, how many of them were broken by idiots flogging them on 87.

It's EASY to argue that idiots can break things by abusing them idiotically. Underdogs can be dunderdogs.
I just don't want to let GM off the hook for being GM - I still remember the Cimarron.
We'd all be far more impressed with GM if there were more 6.2L V8s around to enjoy.

 

[91RS]

Uhh, ok. You can’t tell the difference between an engine designed for towing (torque, lower compression ratio) and an engine designed for performance (power, higher compression ratio)? They have completely different use purposes, you seem like a smart guy, it shouldn’t be hard to figure out. High compression ratios need premium fuel across all brands. There is a reason different octanes exist and are all sold at the same gas stations. If running the correct fuel in the engine bothers you that much, buy a 5.3L and you can safely run 87 all day.

 

[swathdiver]

The trucks do not calculate the grade of fuel and run an appropriate table. The computer advances the timing until it detects knock or pre-ignition and then it pulls timing. Rinse and repeat accelerating from every traffic light, on-ramp and passing a car on the highway, etc..

Our trucks are so well insulated and we're so far removed from the engine that you'll rarely, if ever, hear the motor knock. You fellas running 87, I challenge you to set up your OBDII adapter and app on your phone to display the timing, knock and knock retard.

As for me and my house, all of my Gen IV LS engines run 93 or E85. Even my lawn mower, generator, chainsaw and edger runs fantastic on 93 as well.

 

[swathdiver]

I just don't want to let GM off the hook for being GM - I still remember the Cimarron.

What was wrong with a Caddy Cavalier?

Love my 6.2s, they put a smile on my face every time we get behind the wheel!

 

[Marky Dissod]

You can’t tell the difference between an engine designed for towing (torque, lower compression ratio),
and an engine designed for performance (power, higher compression ratio)?
They have completely different use purposes, you seem like a smart guy, it shouldn’t be hard to figure out.
High compression ratios need premium fuel across all brands.

There is a reason different octanes exist and are all sold at the same gas stations.

TODAY, the reason is because GM failed to write the Low Octane table properly,
and lower the peak ratings as a consequence of using 87.

You're likely smarter than I. It's not as simple as me disagreeing with any of you.
I get why it would be harder to consider the possibility of writing ignition table expecting lower octane to protect an engine,
than to just use 91 or 93.

The trucks do not calculate the grade of fuel and run
an appropriate table.
The computer advances the timing until it detects knock or pre-ignition, and then it pulls timing.
Rinse and repeat accelerating from every traffic light, on-ramp and passing a car on the highway, etc.

Every pcm since the LS1 pcm has TWO ignition timing tables - Low Octane and High Octane -
not AN appropriate table.
However, the pcm interpolates between the two tables essentially as you say it does.
In other words, if the Low Octane Table does not go low enough, or the High Octane table goes too high - OR BOTH -
then the engine cannot run safely on 87 unless the driver is a featherfoot.

If either or both spark tables had been written properly by GM in the first place,
every 6.2L would be able to safely utilize 87, albeit at reduced power.

 

[swathdiver]

TODAY, the reason is because GM failed to write the Low Octane table properly,
and lower the peak ratings as a consequence of using 87.

You're likely smarter than I. It's not as simple as me disagreeing with any of you.
I get why it would be harder to consider the possibility of writing ignition table expecting lower octane to protect an engine,
than to just use 91 or 93.Every pcm since the LS1 pcm has TWO ignition timing tables - Low Octane and High Octane -
not AN appropriate table.
However, the pcm interpolates between the two tables essentially as you say it does.
In other words, if the Low Octane Table does not go low enough, or the High Octane table goes too high - OR BOTH -
then the engine cannot run safely on 87 unless the driver is a featherfoot.

If either or both spark tables had been written properly by GM in the first place,
every 6.2L would be able to safely utilize 87, albeit at reduced power.

I don't think those old computers had the ability to do that. We've only recently seen Toyota and Ram if memory serves do that with some of their vehicles.

I'm aware of the tables, sort of, I thought there was one for gas and one for E85 on the 900s.

To my way of thinking, there would have to be some kind of sensor to detect the octane rating of the fuel and then run the appropriate table.

Maybe they could have written a program to permanently pull timing if there was so much knock retard under such and such conditions and not reset until a refueling event was detected. I would think that all that work would slow down the responsiveness of the system and possibly the engine's reaction to such changing conditions. Just speculating, I'm no automotive software engineer but did stay at a Holiday Inn Express once or twice!

 

[Bagherra]

So if i use 91 or 93 will i notice a significant increase in power over 87??