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6.2l Fuel Question

mojo85

By mojo85
in Engines & Drivetrain

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mojo85 Enthusiast

mojo85

Posted
Posted

Picking up my 6.2l Denali tomorrow and brought up the premium fuel for the 6.2l. The salesman said he never recommends premium and was told not to as it can mess up the timing in the vehicles. He said this was taught to him when the vehicles were rolled out. I brought up that i've read the 6.2l need premium and showed him the sticker on the gas cap (which was inside the truck, the replacement chrome one is currently on it) so he ran in and talked to his lead tech who said regular won't hurt it and the premium may give more power but regular will do no harm. He said it won't impact any warranty at all.

 

This goes against what i've been reading here, is there truth to what he says? That the 6.2l does not require premium fuel?

TechSTL Enthusiast

TechSTL

Posted
Posted

Octane rating is essentially the substance's resistance to igniting before the spark plug fires. Ignition timing (when spark plug fires) is controlled by the computer in the vehicle. There is a base value for ignition timing at a given RPM and load but there are also modifiers (+/-) for this value based upon engine temperature, ambient temperature, and others. In short, your ignition timing varies based upon driving conditions. If there were ever a condition where the computer detects that the mixture in the cylinder is igniting BEFORE the spark plug fires (aka the octane rating is too low), the computer will adjust the effective spark advance. Generally, this condition (called pre-ignition, pre-detonation, pinging, spark knock, etc.) is terrible for an engine. However, the computer works very quickly to correct these conditions on its own to prevent damage to your engine. This ability to take corrective action on the fly means that there really is minimal risk of 87 octane from causing damage to your engine. The base timing values for stock vehicles assume that the customer will forget to use premium or will get bad gas here and there.

 

For most owners who use their truck like a car, running 87 octane won't provide any noticeable loss in performance or measurable damage to the engine. However, if you plan to work your truck hard, especially in hot summer months, you should use premium so you don't end up in a situation where the computer is constantly trying to stop/prevent pre-ignition.

 

Just FYI, your engine will actually be more powerful with the lowest octane rating fuel that does not cause pre-ignition. Without spending lots of time data logging a 6.2L truck, it's not really possible to say if premium fuel is a waste of money.

pm26 Senior Enthusiast

pm26

Posted
Posted

Your salesman is wrong. The correct wording is that "premium is recommended for the 6.2 engine for maximum performance." Today's engines have knock sensors and automatically retard ignition timing when lower octance fuel is used to prevent pinging. You can use regular gas in the 6.2 engine, but it will perform better with the premium fuel and most likely deliver better mileage.

TechSTL Enthusiast

TechSTL

Posted
Posted

Anytime this topic comes up, someone seems to chime in about "octane booster". I'll grab some popcorn and wait patiently. :)

mojo85 Enthusiast

mojo85

Posted
  • Author
Posted

Thanks for the replies, makes things a lot clearer for someone whos truck knowledge is limited

RyanbabZ71 Senior Enthusiast

RyanbabZ71

Posted
Posted

Walk your salesman to your truck, open the fuel door and point to where it says premium recommended. Ask him if he knows more than the engineers at General Motors

 

 

Ryan

haider320 Enthusiast

haider320

Posted
Posted

Your salesman is wrong. The correct wording is that "premium is recommended for the 6.2 engine for maximum performance." Today's engines have knock sensors and automatically retard ignition timing when lower octance fuel is used to prevent pinging. You can use regular gas in the 6.2 engine, but it will perform better with the premium fuel and most likely deliver better mileage.

 

This^

d6007 Enthusiast

d6007

Posted
Posted

I consistently get 17.5 mpg with my 6.2 when running premium, when I run 87, I get 13.5. May be total coincidence but driving conditions were identical. It may be in my head but truck just seems to run better on premium.

captras Enthusiast

captras

Posted
Posted

I would show this to your salesman and get him to give you his statement in writing. From page 9-72 of the Chevy Silverado Owners Manual.

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TJay74 Senior Enthusiast

TJay74

Posted
Posted

If I was going to run anything less than 91/93 it would only during the winter months, once it warms up I would only run 91/93.

temmert1 Enthusiast

temmert1

Posted
Posted

The new 6.2 may be different but my 2010 Sierra ran like crap on 87. I would especially notice it at start up. Engine would almost stall then surge a few times until you started driving. But on 93 octane and at BB tune...........Shut up and hang on!!!!!!!!! :driving:

Fuel mileage, best I ever got was 17.5 round trip.......

captras Enthusiast

captras

Posted
Posted

My last tank average was 19.2 MPG on premium gas. That is daily commute of 18 miles each way about 60%/40% hwy/city mix.

mojo85 Enthusiast

mojo85

Posted
  • Author
Posted

I would show this to your salesman and get him to give you his statement in writing. From page 9-72 of the Chevy Silverado Owners Manual.

 

 

Well damn now im confused again if 87 will cause issues. Where I drive it 87 regular costs $1.70 a litre...

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