Running reg or medium grade fuel with the 6.2?

[Jon A]

I’m not sure you know what detonation is or how destructive it can be. If bad enough it can destroy you engine in a few minutes. If mild, it can slowly destroy your engine over time. It has nothing to do with being “clean” or not. Broken ring lands are just as bad if they’re clean or dirty.

 

And yes, upon teardown it is easy to tell an engine was killed from detonation. And if you still have 87 in the tank….

 

The knock sensor are there to try and protect the engine the same way your seatbelt and airbag are there to protect you. You don’t want to get into a head on collision every day because you have a seatbelt protecting you. An engine heavily detonating is not likely to be saved for very long by the knock sensors. They are reactive, not proactive.

 

Yes, if the KR is only 1-2 degrees it means the severity of the “knocking” is not that great and the engine will likely live for a long time that way. That does not mean it’s ideal or that the engine wouldn’t last longer if it was eliminated with a proper tune/higher octane gas. If it’s a lot more than that you are putting the engine at serious risk.

 

To answer the OP’s question, I have found my 6.2 had quite a bit of KR running on 92 octane at sea level. Not large amounts (1-3 max degrees typically), but it happened quite often, all over the timing map. Running lower octane under those conditions would have been seriously risking damage to the engine.

 

I painstakingly re-tuned the timing map to completely eliminate KR when running 92 octane at sea level. I’ve tested this same tune on 91 octane but only at higher altitudes ~4000+ ft. It’s possible this tune would only have a small amount of KR on lower octane (better than stock anyway) but I haven’t tried as there’s really no point.

 

Yes, I could pull even more timing and probably come up with an 87 or 89 octane tune that would be safer than running a ton of KR all the time, but as mentioned above by others power and mileage would suck so there’s really no point.

 

Some may mistakenly believe if they are at higher altitude they can run lower octane gas. I would caution against this as well due to the way these newer engines are programmed. Yes, less air will fill the cylinders resulting in lower cylinder pressures.

 

The problem is the engine knows this and adds timing accordingly. You really aren’t running on the same “tune” when you’re at altitude as you are when you’re at sea level. Under identical conditions you’re on a different part of the timing map. So if the entire timing map has been set up optimally for a certain octane (I’m not sure how many tuners actually do this), you’ll be running optimally for that octane at all elevations.

 

In short, there is no way I’d recommend running lower than 91 octane in this engine except in case of an emergency. If you have to, keep your foot out of the throttle, try not to lug it, etc. Running with a scanner so you can monitor KR would help and is probably something you should do anyway if you’re contemplating this (it’ll likely change your mind).

[Isriam]

You're not getting it. There have been 0 engine issues to date published or posted based on running 87 or 89 octane in a 6.2L 2014 or 2015. I don't know how much simpler it could get. If you must run 91 or higher the OM would say so, however it doesn't it says you SHOULD. I don't think anyone wanting the engine to last 5+ years would run less than 91, but has it caused problems to date? no.

 

Its kinda like everything else in life, you shouldn't eat 3lbs of bacon, you shouldn't drink 32oz of soda.....

[Jon A]

You're not getting it. There have been 0 engine issues to date published or posted based on running 87 or 89 octane in a 6.2L 2014 or 2015. I don't know how much simpler it could get.

 

That's probably because nobody does it. And the engines are practically new. Run 87 in yours for 100,000 miles (if it lives that long), do lots of towing and other hard use, then put it on a dyno to show how well it's running, tear it down and show no detonation-rlated damage has occurred. THEN, you'll actually have some evidence to back up your claims. Right now you don't.

 

 

If you must run 91 or higher the OM would say so, however it doesn't it says you SHOULD.

 

I'm not sure where you're getting that. It seems pretty clear. Page 9-63:

 

 

If the vehicle has the 6.2L V8 engine

(VIN Code J), use premium

unleaded gasoline meeting ASTM

specification D4814 with a posted

octane rating of 91 or higher. If the

octane is less than 91, damage to

the engine may occur and may void

the vehicle warranty. If heavy

knocking is heard when using

gasoline rated at 91 octane or

higher, the engine needs service.

[Chad2815]

Ran 89 in mine once out of curiosity and it ran horrible, personally I don't know why you would pay an extra 2 grand for an engine that clearly states it needs 91. If you want to be down on power and run 87 that's why they make the 5.3....to each his own though.

[Isriam]

 

 

I'm not sure where you're getting that. It seems pretty clear. Page 9-63:

 

 

 

If the vehicle has the 6.2L V8 engine (VIN Code J), use premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. Regular unleaded gasoline rated at 87 octane or higher can be used, but acceleration and fuel economy will be reduced, and an audible knocking noise may be heard. If this occurs, use a gasoline rated at 91 octane or higher as soon as possible. Otherwise, the engine could be damaged.

 

Once again, it says you can run 87 octane. It does not say you must, and it does not say it will void your warranty.

 

http://www.gmc.com/content/dam/GMC/global/master/nscwebsite/en/home/Owners/Manuals/01_Images/2015-sierra-denali-owners-manual.pdf

[fbachman]

If 91 is "recommended", use it. Timing isn't the only variable ref pre-detonation. In fact, not all fuels are created equal. Based on engine logs I have, I wouldn't run Shell (93) in a rented lawn mower. KR like nobodies business. Run that and your 6.1 will knock like a marocca.

 

Resistance to ignition (i.e. Octane rating) is NEVER a bad thing. Yes, the knock sensors and controls can manage a LOT. But, running high octane fuel, maybe poorly formulated fuel on top of that, and aggravating the situation to induce knock can still cause it to occur, even with higher octane fuels. It has happened occasionally in my truck, and it's a 5.3 (tuned, but still a 5.3).

 

Mileage decreases can occur in any grade fuel, as well, with ethanol blended in (here in OH they don't even have to tell you until it gets > 10% as far as I know). Lowers the heating value, so raises mileage.

 

I have had the best performance with Exxon and BP 93 fuel.

 

As a previous poster indicated... I mean, $7 a tank diff for a $60k truck? I know what I would do. It may not be a catastrophic failure of the engine, but will reduce longevity possibly. Why risk it?

[amxguy1970]

 

 

Please don't listen to this guy, I mean unless he is going to write you a blank check in case you destroy your motor.

 

GM doesn't require premium, it won't destroy your motor If it did they wouldn't have a given it a 100k powertrain warranty and fuel recommendation not requirement of premium. Shoot even the LT1 in the vette doesn't "require" premium...

 

Pretty sure they ran the trucks overloaded in the mountain desert testing on regular fuel to be sure it won't "blow up". If it were me and I was regular towing a good load then ya, I would put in 93 for the few extra HP and a little more peace of mind, most the time though for DD I wouldn't bother for that extra mpg and few more ponies.

 

Tyler

[milligan]

Funny enough, there are a lot of gas stations that don't offer anything above 89 in my area. I can get 93, but I have to be selective. Still getting used to the idea of a truck that requires premium gas

[Jon A]

 

If the vehicle has the 6.2L V8 engine (VIN Code J), use premium unleaded gasoline meeting ASTM specification D4814 with a posted octane rating of 91 or higher. Regular unleaded gasoline rated at 87 octane or higher can be used, but acceleration and fuel economy will be reduced, and an audible knocking noise may be heard. If this occurs, use a gasoline rated at 91 octane or higher as soon as possible. Otherwise, the engine could be damaged.

 

Once again, it says you can run 87 octane. It does not say you must, and it does not say it will void your warranty.

 

http://www.gmc.com/content/dam/GMC/global/master/nscwebsite/en/home/Owners/Manuals/01_Images/2015-sierra-denali-owners-manual.pdf

 

Yeah, the Denali manual still has the outdated carry-over language from the 2013 manual. When I got mine it still had pictures of the 2013 interior and instructions on how to operate the old HVAC and radio, etc.

 

My Denali is also a Sierra. They have updated the Sierra manual: http://www.gmc.com/content/dam/GMC/global/master/nscwebsite/en/home/Owners/Manuals/01_Images/2015-sierra-1500-owners-manual.pdf

 

Once again it says:

 

 

If the vehicle has the 6.2L V8 engine

(VIN Code J), use premium

unleaded gasoline meeting ASTM

specification D4814 with a posted

octane rating of 91 or higher. If the

octane is less than 91, damage to

the engine may occur and may void

the vehicle warranty. If heavy

knocking is heard when using

gasoline rated at 91 octane or

higher, the engine needs service.

 

 

We all have brains. Some choose to use them. Here you have an obvious conflict. What's the smart thing to do here? Are you an engine builder or one who has studied this subject in great depth to the point you feel your expertise carries some authority? Before answering "yes" too quickly, remember we have read your prior posts....

 

If you want to beat the hell out of your engine and make yourself feel better because you found an obsolete/misprint cut-and-paste from an old manual in the new one, that's fine. More power to you.

 

But to advise that others do such a thing in public, is something different. Don't be offended when people say your advice is not something wise to follow.

 

 

 

Pretty sure they ran the trucks overloaded in the mountain desert testing on regular fuel to be sure it won't "blow up". If it were me and I was regular towing a good load then ya, I would put in 93 for the few extra HP and a little more peace of mind, most the time though for DD I wouldn't bother for that extra mpg and few more ponies.

 

How exactly are you "pretty sure?" I know "Government Motors" got a lot of our tax money, but enough to give their Powertrain Engineers an unlimited budget to test stupid stuff that's not one of their design requirements? Don't they wish! Things just don't work that way in the real world. If these companies gave us Engineers all the money we needed to test all the things we felt like testing they would go out of business. Long-term durability testing an engine designed to use premium gas on non-premium gas would be a colossal waste of money.

[Isriam]

Your condescending attitude is rude. If you read the topic of the post you'd know the Op wasn't asking what the manual said. He was asking has anyone, and if so did they have any troubles. The answer to his question is in this thread, and not in your post. You're trying to tell me to run premium because it can break my engine. I already stated that I do run 93 and why. Regardless of what your manual says, many thousands of people have a manual that says different. If a consumer took GM to court, they would win. So what is your actual point in this thread other than insulting others? Your stance has been spoken by others in this thread including me. You should not run 87, but if you do you MIGHT can expect trouble down the road, but to date no one has reported any issues on this forum.

 

 

anyone running reg or mediumm grade fuel with the 6.2? if so any trou

[Jon A]

 

Your condescending attitude is rude.

 

Your first words in this thread were "don't listen to these guys." How would you describe that?

 

 

If a consumer took GM to court, they would win.

 

If they are driving a new Sierra where the manual says they'll void their warranty if using less than 91? How do you figure that?

 

 

So what is your actual point in this thread other than insulting others?

 

Allowing people to make a more informed choice by providing information. You were giving incorrect information that may encourage people to do something that damages their engine. That's not an insult, it's a statement of fact.

[Isriam]

 

 

You were giving incorrect information that may encourage people to do something that damages their engine. That's not an insult, it's a statement of fact.

 

Again, please prove that running 87 octane in this engine can and has harmed it. I quoted my context directly from the GMC Denali owners manual along with a link to it. That is directly from GMC's site. You can say that you think it will damage it, but in fact KR in the computer will probably allow the engine to run hundreds of thousands of miles on 87 octane just fine.

 

Dont confuse my posts that say yes you can, with yes you should.

[KARNUT]

It's just around 5 $ per tank more to run the good stuff, why chance it? I fill up at 1/2 of tank anyway so if I can t get the good stuff no problem. I have a 5.3 so I only run 93 grade when I can't get E 85, it just runs better on it.

 

 

Sent from my iPhone using Tapatalk

[FeelTheThunder]

I accidentally ran regular twice in my 2011 6.2L and did not notice a difference. Maybe not the whole tank though and I was highway driving.

In my manual it says it is ok.

I will be running premium in my new one 100%

 

 

2011 Silverado manual

 

If the vehicle has the 6.2L V8 engine
(VIN Code 2), use premium
unleaded gasoline with a posted
octane rating of 91 or higher. You
can also use regular unleaded
gasoline rated at 87 octane or
higher, but the vehicle's acceleration
could be slightly reduced, and a
slight audible knocking noise,
commonly referred to as spark
knock, might be heard.

 

2015 Silverado Manual

 

If the vehicle has the 6.2L V8 engine
(VIN Code J), use premium
unleaded gasoline meeting ASTM
specification D4814 with a posted
octane rating of 91 or higher.
Regular unleaded gasoline rated at
87 octane or higher can be used,
but acceleration and fuel economy
will be reduced, and an audible
knocking noise may be heard.

[haider320]

I won't even use 87 in my 5.3 due to the high compression ratio in these engines.