6.2 Engine: To Premium Or Not, Facts Here

[truck_newbie]

There have been multiple threads/posts on what fuel to feed the 6.2 beast. Since GM only recommends premium fuel, it’s become a gray area and most people don’t like gray areas. Not surprisingly, there are passionate opinions on either side. I for one am a facts guy and prefer to go with actual numbers rather than some romantic notions of what someone thinks. It turns out this experiment has already been done for the L86 engine. Our engine is the L87 but it makes the same power and torque as the L86 and it seems the only difference is the addition of DFM for the L87.

 

 

Summary below

1.       Knock: No audible knock was observed with regular fuel.

2.       Power: Reduction in power was average of 0.7% which evaluates to 2.94hp. I was actually quite surprised by this, I was expecting more. If you claim you can tell a 0.7% difference, then more power to you.

3.       MPG: The biggest gain was fuel economy. They recorded an average of 7.1% reduction in mpg with regular. If you live in an area where premium fuel cost is less than 7.1%, then by all means go for it. Where I live, premium is $15 more on a $45 regular fill-up.

 

I’m not here to tell you what fuel to feed your 6.2 but if you prefer numbers like me, then maybe this can help you make an educated decision. Will probably get some flak for this but that’s ok.

 

AAA Report

 

 

[spizike9]

Good info. Thanks for the post. 

[Black02Silverado]

I'm old school and the compression ration on these engines being what it is, back in the day premium was the only thing you ran to keep from destroying the engine  from pre-ignition.   Now today we have computers and direct injection along with fancy variable valves.  But I still say compression is compression and fuel ignition still are the same.  If you want to make sure your engine lives long and you plan on keeping it, paying the extra for premium is the only way to go.

 

Now if you trade every three years then it wouldn't matter.  Justin at Black Bear Performance even stated that to at least run mid grade.  He see's what goes on inside the computer and how the engine reacts.  So his recommendation is based on his trade of tuning and seeing what comes through is email on individuals sending in tune files and I'm sure he can tell who runs what grade of fuel by the engine file.

 

Just my opinion.

Edited August 28, 2019 by Black02Silverado

[BlueAT4]

Using Premium Unleaded Gas in my AT4 had failed to produce an increase in gas milage. Simple math makes 87 octane the best fuel to use. 

[eppieguy]

Justin used to tell me the same with my 5.3 Tahoes, seems the gas in my area was crap and he said that I should run at least 89 based on what he saw on his computer. 

[truck_newbie]

14 minutes ago, Black02Silverado said:

I'm old school and the compression ration on these engines being what it is, back in the day premium was the only thing you ran to keep from destroying the engine  from pre-ignition.   Now today we have computers and direct injection along with fancy variable valves.  But I still say compression is compression and fuel ignition still are the same.  If you want to make sure your engine lives long and you plan on keeping it, paying the extra for premium is the only way to go.

 

Now if you trade every three years then it wouldn't matter.  Justin at Black Bear Performance even stated that to at least run mid grade.  He see's what goes on inside the computer and how the engine reacts.  So his recommendation is based on his trade of tuning and seeing what comes through is email on individuals sending in tune files and I'm sure he can tell who runs what grade of fuel by the engine file.

 

Just my opinion.

I can understand tuning requiring premium. Is he saying the same for an un-tuned factory car? If so, what facts is he basing this on?

 

There are other advantages to premium such as more detergents. The detergents argument matters less these days because of direct injection so you are going to get carbon build-up on the valves either way. 

Edited August 28, 2019 by truck_newbie

[truck_newbie]

14 minutes ago, BlueAT4 said:

Using Premium Unleaded Gas in my AT4 had failed to produce an increase in gas milage. Simple math makes 87 octane the best fuel to use. 

Personally, i saw a 1.5 mpg improvement when i used premium. Didn't notice any other difference. 

[Mountain boy]

The computer can and will compensate for lower octane fuel, it will retard the timing to prevent knock. This absolutely will reduce performance and if you get some really bad 87 you may experience knock and you may not hear it. It’s your truck but there is a reason GM recommends higher octane, it might only be for better performance, but isn’t that why you bought the 6.2.

[aseibel]

I don't know why anyone would choose to pay extra for a 6.2 and then put 87 in it. There are plenty of 5.3's available for the cost conscious consumer.

 

But if you do have a 6.2 and are more concerned with cost of fuel/mile, you are not coming out ahead by paying for 93 octane. Any small gains do not offset the extra cost.

 

Just like anyone with a 5.3 who buys premium fuel won't notice any benefits either.

 

Put in the gas you want, its your truck.

[Texas Daddy]

High compression (over 9.6:1) requiring premium is for NON direct injection engines. For the 2014-18, compression on stock 5.3 L83 and 6.2 L86 direct injection engines are both 11:1, yet 5.3 did not require premium. DI changes everything, as pre-ignition can be mitigated, so I imagine there is no real need for premium in the 6.2. Awesome to see 0-60 in 5.4 seconds from car and driver from the 6.2 in a 19 4x4 crew cab; thats like a fuggin supercar in the 80s, lol...

Sent from my SM-T580 using Tapatalk

[killramos]

Is the 6.2 11.5:1? Versus 11:1 in 5.3.

 

https://www.gm-trucks.com/forums/topic/212098-official-2019-53l-62l-v8-engine-specs-are-here/

[Joe98]

2 hours ago, spizike9 said:

Good info. Thanks for the post. 

I second this... thanks.  

[Black02Silverado]

2 hours ago, truck_newbie said:

I can understand tuning requiring premium. Is he saying the same for an un-tuned factory car? If so, what facts is he basing this on?

 

There are other advantages to premium such as more detergents. The detergents argument matters less these days because of direct injection so you are going to get carbon build-up on the valves either way. 

Not sure exactly why and it is for stock because I was asking about our 2016 Suburban and getting a tune for it eventually. Best is to email Justin.

[gone_fishing]

3 hours ago, truck_newbie said:

Personally, i saw a 1.5 mpg improvement when i used premium. Didn't notice any other difference. 

Do you know if the premium fuel was ethanol free? In my area, premium (91 octane) gas is available with ethanol (E10) or without (E0). Just depends on the station. E10 91 octane is generally less expensive then E0. Seems like E0 will usually gain you a little fuel economy. I believe that is because it has more energy (BTU's). Adding ethanol reduces it's energy content but is also cheaper. Hard to say if it pencils out.

 

I'm far from a tuning expert but do monitor timing advance and knock retard with a ScanGauge device. From what I have learned watching these numbers is the computer always seems to want to maximize timing advance as much as possible. If it picks up a few degrees of KR, it backs off timing advance (as it should). From a fuel economy stand point, I imagine the engine is more efficient when the timing is advanced? Even when cruising with a light load (flat road, no wind, not towing) a slight increase in load (incline of a bridge or overpass) can sometimes cause a little KR. Seems like the computer is always trying to push the limit a little. Read somewhere that is does "learn" where it can operate. I wonder if a 6.2 can "learn" to run on 87?

[Roscopcoletrain]

My truck knocked on 87. I only run 91 now