Deactivate DFM & Use 87 Octane Gas With 2022 6.2L L87 Motor?

Workdog · March 11, 2022

New guy here, so, I'm sorry if this has been covered before. Looking at ordering a 2022 Silverado RST with the 6.2L L87 motor. Recommended fuel is 91 octane. If DFM is disabled, would it make sense to use 87 octane fuel? Bottomline...is the 91 octane directed because of the DFM causing cylinders to shut down? The 6.6L gas motors in the 3/4 ton HDs do NOT have DFM and their recommended fuel usage is 87. What say you?

TNTSierra · March 11, 2022

NO! The 6.2L motor is designed for maximum performance, effectiveness, and longevity with 91+ octane. Turning off DFM will not do a thing for the use of premium fuel. If you are worried about premium fuel, I suggest a 5.3L with the 10 speed. Step dad has it and loves it.

JimCost2014 · March 11, 2022

Bottomline...is the 91 octane directed because of the DFM causing cylinders to shut down?

No. If you are new to the GM trucks, and especially the 6.2 platform, maybe do some research before making the investment.

It is a great engine, but you should run the high octane so you get what you paid for. Maybe like the above post suggested, 5.3.

May be a better way to go for your driving needs, if fuel price is an issue.

Edited March 22, 2022 by JimCost2014

rbdjr · March 11, 2022

My 2020 corvette recommends High Octane fuel also, I run 87 as I only drive on weekends and not a big hurry, I believe unless you’re on the strip you will have no problems . Knock sensor will make fuel and timing adjustments long before the human ear can hear it.

redwngr · March 11, 2022

Kind of a waste ponying up the extra cash for the 6.2 and then preventing it from performing to it's abilities by running regular fuel.

AirForceAngler · March 11, 2022

DFM has absolutely nothing to do with octane requirements. Octane requirements are a result of compression ratios and the 6.2 has 11.5:1 compression. The 5.3 and 6.6 have around 10:1 or so. The higher the compression, the higher the octane requirement. Octane ratings are a measure of a fuel's resistance to pre-detonation. Higher compression also increases the heat in the cylinder as the piston moves up and lower octane fuels can ignite too soon; pre-detonation.

newdude · March 11, 2022

2 hours ago, Workdog said:

New guy here, so, I'm sorry if this has been covered before. Looking at ordering a 2022 Silverado RST with the 6.2L L87 motor. Recommended fuel is 91 octane. If DFM is disabled, would it make sense to use 87 octane fuel? Bottomline...is the 91 octane directed because of the DFM causing cylinders to shut down? The 6.6L gas motors in the 3/4 ton HDs do NOT have DFM and their recommended fuel usage is 87. What say you?

NO. Not at all. DFM and octane are NOT connected. 6.2 is a high compression performance engine and needs 91+octane to operate properly.

6.2 *can* be run on 87 octane but can be detrimental to engine life.

91+octane is a must for the 6.2.

If operating costs (fuel) are of concern, I'd look at the 5.3 or the 2.7 Turbo 4.

Workdog · March 12, 2022

AirForceAngler-- Clear and well stated! Thanks.

I'm pulling a boat and looking for a non-turbo, 6+ L motor. I've had 5.3Ls before and don't want that. I'll just go with the 3/4 ton with the 6.6L gas motor. Pricing them out, I can go with the 2500 and roughly the same desired equipment for $4,000 less than the RST. I currently have a 2500 with a 6.0 motor.

TNTSierra · March 12, 2022

21 minutes ago, Workdog said:

AirForceAngler-- Clear and well stated! Thanks.

I'm pulling a boat and looking for a non-turbo, 6+ L motor. I've had 5.3Ls before and don't want that. I'll just go with the 3/4 ton with the 6.6L gas motor. Pricing them out, I can go with the 2500 and roughly the same desired equipment for $4,000 less than the RST. I currently have a 2500 with a 6.0 motor.

The new 5.3L is nothing compared to the older ones. I had two -K2 5.3L. One with a 6 speed and one with 8 speed. Even though HP/TQ stayed the same between 2014-2022. The 2019 and up T1s perform way better. Go take one for a spin. I was greatly surprised with stepdads new Sierra

redwngr · March 12, 2022

2022 V8 gas used in pickups:

L8T Engine, 6.6L V8 with Direct Injection and Variable Valve Timing, gasoline, (401 hp [299 kW] @ 5200 rpm, 464 lb-ft of torque [629 N-m] @ 4000 rpm)

L87 Engine, 6.2L EcoTec3 V8, (420 hp [313 kW] @ 5600 rpm, 460 lb-ft of torque [624 Nm] @ 4100 rpm); featuring Dynamic Fuel Management that enables the engine to operate in 17 different patterns between 2 and 8 cylinders, depending on demand, to optimize power delivery and efficiency

L84 Engine, 5.3L EcoTec3 V8, (355 hp [265 kW] @ 5600 rpm, 383 lb-ft of torque [518 Nm] @ 4100 rpm); featuring available Dynamic Fuel Management that enables the engine to operate in 17 different patterns between 2 and 8 cylinders, depending on demand, to optimize power delivery and efficiency

And just for fun, the standard 1500 motor for some trims

L3B Engine, 2.7L Turbo High-Output, (310 hp [231 kW] @ 5600 rpm, 430 lb-ft of torque [583 Nm] @ 3000 rpm)

The 6.6 uses a the 6 speed.

The 2.7 uses an 8 speed

The 5.3 and 6.2 get a 10 speed

Edited March 12, 2022 by redwngr

CamGTP · March 12, 2022

Just so we are accurate the 5.3's have 11.0:1 compression ratio and the 6.2's have 11.5:1 compression.

That .5 in compression doesn't really make that much of a difference. Yes the 6.2 will make the most power on 91+ octane but running 87 or 89 octane can be done and people do it all the time.

I've seen data logs of 6.2's on lower octane fuel and they do fine. Sure it spark knocks a little bit more only under heavy load but the computer can handle that. The engine doesn't know what octane it's running when at cruising speeds where people spend 99% of their time driving.

Byrds8 · March 12, 2022

A lot of info in this thread concerning 87 Octane in the 6.2L

Workdog · March 12, 2022

Good info everybody! Thanks for the inputs. I just placed an order for a 2500 LT with the 6.6L gas engine. In 3 years the truck will be paid for. However, with a 6.2L I would still be paying $20 a tank more for gas. And, many of the gas stations I use only have the 87 octane anyways.

Edited March 12, 2022 by Workdog

voided3 · March 12, 2022

4 hours ago, Workdog said:

Good info everybody! Thanks for the inputs. I just placed an order for a 2500 LT with the 6.6L gas engine. In 3 years the truck will be paid for. However, with a 6.2L I would still be paying $20 a tank more for gas. And, many of the gas stations I use only have the 87 octane anyways.

Good call. I really wish we had bought the 2500 Custom 6.6 gas instead of our 1500 LT 5.3 for the same price. I can't stand DFM or auto start/stop so I have to drive in L7 all of the time to disable both.