With the GMC 6.2 can you run just 87 or can you run non ethanol gas or just the 92 oct??

[carhaulereastcoast]

so i watched a video and cant remember where but a guy owned a hell cat red eye and for the life of the car he put in 87 oct and said he had no knocking or power loss. so the question i have is this, if i dont buy the diesel GMC AT4 im going to get the 6.2 AT4. with the guy running 87 in his hell cat makes me think that with the 6.2 it would be ok also??? now we have a couple of non ethanol gas stations here in Columbia SC at just 4.49$ a gallon, lol would this be good and what is this used for outside of racing? thanks and God bless

 

[zonedout]

You will need to run 91+. The engine may not self destruct on 87 but it won't like it, it wants 91 and it absolutely will pull timing giving you less power on 87. If you're stuck in the middle of knowhere without premium, that's one thing, but long term and any sort of performance driving like heavy on the throttle and towing in the summer you need to run 91+.

It's not an enthanol thing, it's an octane thing and 91 is what it wants!

Even my engine which is actually allowed to run 87 doesn't like it, I give it 91 too. I'd never try 87 with a hellcat, don't believe everything you see/read on the internet.

 

[Fightnfire]

I'm a member of a lot of AT4 forums and many people run regular 87 octane with no issues. The truck will learn what fuel it's running off of and pull timing to reduce power mildly. Though in 0 to 60 times it's almost not noticeable. Some engines do develop a knock on 87 but GM has said that doesn't hurt the engine.

My 2021 6.2 AT4 has only ever had premium in it.

Keep in mind for warranty purposes it's a recommendation not a requirement so you don't void the warranty by running 87.

 

[NorthskyBlue NHT]

so i watched a video and cant remember where but a guy owned a hell cat red eye and for the life of the car he put in 87 oct and said he had no knocking or power loss. so the question i have is this, if i dont buy the diesel GMC AT4 im going to get the 6.2 AT4. with the guy running 87 in his hell cat makes me think that with the 6.2 it would be ok also??? now we have a couple of non ethanol gas stations here in Columbia SC at just 4.49$ a gallon, lol would this be good and what is this used for outside of racing? thanks and God bless

The current gen 6.2L (2014+) has always been stated as premium required by GM. If GM thought regular was ok they would have said premium recommended in the manual. The 2013 and earlier 6.2L was premium recommended (not required) because it had a lower compression ratio 10.7:1 vs 11.5:1.

 

[chaseydog]

GMC likely has a reason they are recommending premium gas. After all that recommendation probably hurts sales, so why recommend it if there's no real advantage. Can you get away with 87, I'm guessing you can. But in the end who do you trust more, the engineers that designed the engine, or some random guy on YouTube.

 

[chaseydog]

I'm a member of a lot of AT4 forums and many people run regular 87 octane with no issues. The truck will learn what fuel it's running off of and pull timing to reduce power mildly. Though in 0 to 60 times it's almost not noticeable. Some engines do develop a knock on 87 but GM has said that doesn't hurt the engine.

My 2021 6.2 AT4 has only ever had premium in it.

Keep in mind for warranty purposes it's a recommendation not a requirement so you don't void the warranty by running 87.

What are some of the AT4 forums you recommend?

 

[Dusdaddy]

so i watched a video and cant remember where but a guy owned a hell cat red eye and for the life of the car he put in 87 oct and said he had no knocking or power loss. so the question i have is this, if i dont buy the diesel GMC AT4 im going to get the 6.2 AT4. with the guy running 87 in his hell cat makes me think that with the 6.2 it would be ok also??? now we have a couple of non ethanol gas stations here in Columbia SC at just 4.49$ a gallon, lol would this be good and what is this used for outside of racing? thanks and God bless

I'm with others. Higher compression, run the higher octane. When I bumped the compression on my Jeep over 10 she loved premium. I can see over 11 requiring it.

 

[Fightnfire]

The current gen 6.2L (2014+) has always been stated as premium required by GM. If GM thought regular was ok they would have said premium recommended in the manual. The 2013 and earlier 6.2L was premium recommended (not required) because it had a lower compression ratio 10.7:1 vs 11.5:1.

That's not accurate, I own a 2021 it's a recommendation not a requirement.

 

[zonedout]

The 6.2 actually recommends 93, not just 91.

We're playing games with words here. "Recommends", "Requires", the point is that the truck really really wants high octane fuel and it will have knock and detonation without it. This is not something that is good for the engine long term unless you like wiggly wrist pins, bent connecting rods, and aluminium in your oil.

 

[carhaulereastcoast]

That's not accurate, I own a 2021 it's a recommendation not a requirement.

I think the biggest thing I need to come to grips with is this with the price of diesel just 14 cents more than the 92 here in SC, do I want the MPG or the HP? with the foot pounds with that diesel you are almost not losing much of anything but some MPG. all my wife wants is duel comfort so she can have her side 90 with mine at 60 lol

 

[Fightnfire]

The 6.2 actually recommends 93, not just 91.

We're playing games with words here. "Recommends", "Requires", the point is that the truck really really wants high octane fuel and it will have knock and detonation without it. This is not something that is good for the engine long term unless you like wiggly wrist pins, bent connecting rods, and aluminium in your oil.

That's not always true either I've stood next to and driven in a few different GM 6.2s running on 87 and you can't notice the difference. There is always a chance a specific motor could knock slightly on regular fuel but it shouldn't be stated that it will as a fact. I strongly disagree that we're playing with words, The difference between recommend and require is extremely important.

 

[Dusdaddy]

That's not always true either I've stood next to and driven in a few different GM 6.2s running on 87 and you can't notice the difference. There is always a chance a specific motor could knock slightly on regular fuel but it shouldn't be stated that it will as a fact. I strongly disagree that we're playing with words, The difference between recommend and require is extremely important.

Agreed. I think I can count on one hand how many people I've met that run mid-grade in a hemi as recommended. They all work fine. I tried it myself on a long trip to see any difference as well.

 

[Honcho]

That's not always true either I've stood next to and driven in a few different GM 6.2s running on 87 and you can't notice the difference. There is always a chance a specific motor could knock slightly on regular fuel but it shouldn't be stated that it will as a fact. I strongly disagree that we're playing with words, The difference between recommend and require is extremely important.

Have you done any unloaded testing on Fuel economy on your 6.2 between 91 and 87 ? The EPA i think says 1 MPG difference between the 6.2 and the 5.3 . If it turned out to be similar , with the same fuel, the 6.2 would seem to be the best choice .

 

[Fightnfire]

Have you done any unloaded testing on Fuel economy on your 6.2 between 91 and 87 ? The EPA i think says 1 MPG difference between the 6.2 and the 5.3 . If it turned out to be similar , with the same fuel, the 6.2 would seem to be the best choice .

I personally have not. I've only run premium in my truck.

 

[chaseydog]

I think the biggest thing I need to come to grips with is this with the price of diesel just 14 cents more than the 92 here in SC, do I want the MPG or the HP? with the foot pounds with that diesel you are almost not losing much of anything but some MPG. all my wife wants is duel comfort so she can have her side 90 with mine at 60 lol

14 cents is more than I'm seeing in NC, but it's been awhile since I crossed the boarder into SC for fuel. I'm typically seeing diesel an premium within 1 or 2 cents of each other, though to be fair I can find stations near me that are changing 10 cents higher for diesel, but they are not stations I use

 

[Fightnfire]

In the PNW diesel is higher, I don't have an actual number, I'll look into it.

 

[zonedout]

That's not always true either I've stood next to and driven in a few different GM 6.2s running on 87 and you can't notice the difference. There is always a chance a specific motor could knock slightly on regular fuel but it shouldn't be stated that it will as a fact. I strongly disagree that we're playing with words, The difference between recommend and require is extremely important.

You're not going notice it standing beside it while idling. It happens under load. These knock sensors are reactive, which means by definition the engine knocks/pings FIRST; then it detects it, cuts timing and try's to protect itself.

You're welcome to disagree strongly, but the facts are the facts; these engines have a compression ratio that needs high octane, and it has tuning designed to run on it, it will try to save it self when given poor gas but the engine is always better off not having the poor gas in the first place.

 

[zonedout]

Agreed. I think I can count on one hand how many people I've met that run mid-grade in a hemi as recommended. They all work fine. I tried it myself on a long trip to see any difference as well.

I've had a mechanic sitting in my truck saying "I don't hear ping" and yet it was clear as day to me. "work fine"? You need to define what "fine" means first.

What is a real head scratcher is guys spending 60 to 90 k on a truck and then trying to save 5 bucks on a fill.

Anyway, not going to argue the point any further but these trucks really do do best on high octane.

 

[Fightnfire]

You're not going notice it standing beside it while idling. It happens under load. These knock sensors are reactive, which means by definition the engine knocks/pings FIRST; then it detects it, cuts timing and try's to protect itself.

You're welcome to disagree strongly, but the facts are the facts; these engines have a compression ratio that needs high octane, and it has tuning designed to run on it, it will try to save it self when given poor gas but the engine is always better off not having the poor gas in the first place.

And driven. You missed that part.

There's no disagreement with the concept that it would prefer higher quality fuel and perform better on higher quality fuel I simply wanted to point out your error in words from a previous post that it's required. I double checked my manual to be sure.

If true damage could be done to the motor by driving it off of regular fuel they would require the fuel not just recommend it, they, GM and other manufacturers, don't have a problem saying required when they mean it.

 

[zonedout]

And driven. You missed that part.

There's no disagreement with the concept that it would prefer higher quality fuel and perform better on higher quality fuel I simply wanted to point out your error in words from a previous post that it's required. I double checked my manual to be sure.

I didn't use the word "required".

If true damage could be done to the motor by driving it off of regular fuel they would require the fuel not just recommend it, they, GM and other manufacturers, don't have a problem saying required when they mean it.

My point is that people are hanging onto the "recommended" and "required" while ignoring the obvious truth regardless of which word you want to value most.

You can get away with all kinds of abuse in an engine/truck. Don't hang onto the manual as if its going to save you, higher octane = better for the engine that is an undisputed fact. Running 87 in an engine that recommends 93 is just nuts, there is just not that much wiggle room with the compression ratio, ask any builder/tuner.