Running reg or medium grade fuel with the 6.2?

bwh2003 · March 15, 2015

Again, I think everyone here gets the point except you. Continue on, I'm done proving my point. The manual in thousands and thousands of vehicles says 87 is OK.

Probably a bad idea but I will put my opinion in the thread. The manual you quoted does not say 87 is ok to run in the truck, it states it can be done. Is it a good idea, probably not. The point Jon is trying to make is running 87 is against the updated owners manual and is not a good idea based on potential damage to the engine. What idiot pays extra for the 6.2 and then wants to risk damaging the motor by saving a few cents at the pump? Did you look at the link posted by redwngr? It is well known the 6.2 motor needs premium fuel, not really sure why you are fighting about it. The point is, the 6.2 was designed to run on premium, updated documents show it requires premium, end of story.

LeoS41280 · March 15, 2015

Comes down to do what ya want

SierraBlanca · May 4, 2016

I have a 2016 6.2 L86 in a Sierra. I've been running only 87 octane since new. I've detected no trace of knock and the highway mileage is up around 21mpg. It also has more power than I need but I'm not complaining.

I'm going to try 91 in the future just to see if there is a fuel mileage difference. I have tried 91 in two other direct injected high CR cars I own and have found no difference in mileage. There never was the presence of knocking in either of those cars with 87.

Once I have more real world info I will post. So far I have no evidence that 87 is a problem.

TJay74 · May 4, 2016

Again, I think everyone here gets the point except you. Continue on, I'm done proving my point. The manual in thousands and thousands of vehicles says 87 is OK.

Actually, no it doesn't. The manual says you can use 87 octane but that pinging and audible knocking could be heard and engine damage could occur which would not be covered under warranty. I take that to mean, 87 can be used in an emergency or short use, but to fill up with 91+ octane as soon as possible so to not damage the engine. If you do damage the engine it will not be covered under warranty if it is found the octane is less than 91 (which by the way the ECM does have the ability to record the octane content of the fuel).

You could hear my 6.2 pinging on my new 2016 truck, so as soon as the tank was under half I used a local station and filled up with 100 octane so I could run the tank down and not worry about it.

Also, while the ECM does have the ability to retard timing by dropping into the low octane timing map, the amount of timing that can be retarded is limited. If that timing reduction is not enough to stop the pinging/knocking/KR you could be damaging the engine at that point. The concept of a knock is no different than hitting the top of the piston with a ball peen hammer, normally it tends to leave divots in the piston tops and at times even break the ring lands off of the pistons.

This is like saying the rev limiter protects the engine, while it does it is still possible to mechanically over rev and engine and go past the electronic limiter and damage the engine. So while a safeguard is in place that doesn't mean you should use/abuse it because it catches the issue. It means it can be used a safeguard but to return back to the normal suggest use ASAP.

TJay74 · May 4, 2016

I have a 2016 6.2 L86 in a Sierra. I've been running only 87 octane since new. I've detected no trace of knock and the highway mileage is up around 21mpg. It also has more power than I need but I'm not complaining.

I'm going to try 91 in the future just to see if there is a fuel mileage difference. I have tried 91 in two other direct injected high CR cars I own and have found no difference in mileage. There never was the presence of knocking in either of those cars with 87.

Once I have more real world info I will post. So far I have no evidence that 87 is a problem.

Hearing knock on the engine can be hard at times, it can be heard though and I can promise you that 6.2l is knocking. I have recorded it with scanning software, heard it while driving next to concrete retaining walls. The hotter the weather the easier it is for knock to happen.

In this day and age I hope people know how and why spark knock happens. When the fuel mixture is compressed and it to the point of ignition from the spark plug. a leading edge on the piston or valve is actually hot enough to ignite the mixture early. Milliseconds later the spark plug ignites the mixture as well, now you have two different flame front traveling across the piston face and colliding, that is when the knock sounds occurs. You want one smooth flame front to travel across the piston.

The difference in 87 to 91 octane is the amount of potential energy, 87 octane produces more BTU's of energy and it burns faster as well. 91 octane produces less BTU's of energy and burns slower which helps to keep those leading edges from igniting the mixture early.

camcamaro1991 · May 4, 2016

I agree with TJay74, I have seen HP tuners pull timing b/c of knock when I could not hear it, these trucks are very quite. Dang dealership put 87 octane in my new truck against my will!

I could hear knock while I did my engine break in operating slowly up and full decal from 3-5K rpms, the truck pulled a lot of timing but then settled it, waiting for my first 93 octane fill up to check timing again.

bosro · May 4, 2016

I've had ping using 91 octane....let alone 87

Didnt buy a 6.2L to have decreased performance....

Besides which I have enough joy with shitty 8 speed and highway vibes....dont need any hassle with the engine!!

thetruck454 · May 5, 2016

I strictly run 93 and also monitor knock via obdII. I have seen knock on throttle tip in and when accelerating on the highway, I can only imagine what lower grade fuels can do. Saying I hear no knock is much different than actually monitoring the knock retard via some sort of scan device.

Jeffjr464 · May 5, 2016

If you can afford 80k for a truck don't open your mouth bout the price of gas Shhhh, pay up and drive!!!

SierraBlanca · May 5, 2016

The difference in 87 to 91 octane is the amount of potential energy, 87 octane produces more BTU's of energy and it burns faster as well. 91 octane produces less BTU's of energy and burns slower which helps to keep those leading edges from igniting the mixture early.

Octane rating is a measure of resistance to detonation of a compressed fuel air mixture of known concentration. It does not have anything to do with energy content of the fuel. You are constantly showing your ignorance of the subject at hand. So are the rest who have not presented factual evidence and want to convince the rest of us that their bat like hearing can detect knocking that no one else can.

The engine is direct injected in order to run on lower octane fuels. No one is discussing this fact. Comparisons to other engine types doesn't work.

Here is a line from Ford concerning their ecoboost v6's and fuel type:

"Despite being a high compression forced induction engine, the direct injection fuel system allows the ecoboost to run on 87 octane, regular unleaded gasoline."

The original specs for the engine also show it to run on 87 octane here: http://gmauthority.com/blog/gm/gm-engines/l86/

redwngr · May 5, 2016

GMPowertrain also recommend premium fuel for the L86 but recommend regular fuel for the L83.

http://gmpowertrain.com/VehicleEngines/PowertrainProducts.aspx

SierraBlanca · May 6, 2016

GMPowertrain also recommend premium fuel for the L86 but recommend regular fuel for the L83.

http://gmpowertrain.com/VehicleEngines/PowertrainProducts.aspx

The only engines with specs shown are marine engines and none of them say premium fuel is required.

On this page the L86 is compared to the 3.6 liter V6 LF3. http://gmauthority.com/blog/2013/06/gms-new-6-2-liter-v8-l86-vs-new-3-6-liter-twin-turbo-v6-lf3-by-the-numbers/

Notice that premium is REQUIRED for the LF3. Premium has only been recommended for the L86 and NOT REQUIRED.

thetruck454 · May 6, 2016

What is on my gas cap for what it's worth

redwngr · May 6, 2016

The only engines with specs shown are marine engines and none of them say premium fuel is required.

Not true. Have another look.

The GM powertrain info specifically lists which models the engines are used in. Select an engine from the list and see.

This is a partial ct and paste from the L86 entry. Sorry the formatting doesn't copy across.

Displacement: 6162cc (376 ci)

Engine Orientation: Longitudinal

Compression ratio: 11.5:1

Valve configuration: overhead valves

Valves per cylinder 2

Assembly site: Tonawanda and St. Catherines

Valve lifters: hydraulic roller

Firing order: 1 - 8 - 7 - 2 - 6 - 5 - 4 - 3

Bore x stroke: 103.25 x 92mm

Fuel system: DI

Fuel type: Premium recommended

Maximum Engine Speed: 6000 rpm

Emissions controls: catalytic converter

Three-way catalyst

Positive crankcase ventilation

Applications: Horsepower: hp ( kw )

Chevrolet Silverado

GMC Sierra

Cadillac Escalade, Escalade ESV

GMC Yukon, Yukon XL 420hp (313kW) @ 5600 RPM SAE Certified

Applications: Torque: lb-ft. ( Nm )

Chevrolet Silverado

GMC Sierra

Cadillac Escalade, Escalade ESV

GMC Yukon, Yukon XL 460 lb-ft. (624 Nm) @ 4100 RPM SAE Certified

Click on the product guide to see a 'where built' and 'where used' listing for both engines and transmissions.

.

SierraBlanca · May 6, 2016

Not true. Have another look.

.

Why don't YOU have another look. NONE of the engines specify that premium fuel is REQUIRED. Do you know the difference between recommended and required?

You do not HAVE to use premium fuel in the 6.2l L86. Case closed. Gavel dropped.