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6.2l Fuel Question


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I have a older 6.2 ('11), and switch from premium to regular all the time. I notice the performance difference. If I've been running premium and then switch to regular I hear it knock once and then she detunes and doesn't knock again the whole tank. And I drive her hard. Run what you want.

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Look at it this way: You got that 6.2 liter engine for a reason, so use better fuel to get the full power you paid for! I would use premium fuel in it. Just as I would if I bought a new Camaro or Corvette with the 6.2 liter engine. And I bet that you will get better fuel economy which will offset the fuel cost.

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I am not sure how much stock to put in that reference in the owners manual. The marketing and print guys still haven't gotten it right regarding the use of E-85 in the L86 6.2 My build sheet from GM still lists it as flex fuel, where it has been shown not to be both in person on the truck themselves and in both the early tech references and the service information. I am betting those manuals were printed long before GM started building the trucks let alone the 6.2 equipped trucks.

 

That said my 04 Grand Prix GTP with the supercharged 3800 recommends premium fuel also. I have run both, its not a huge difference in performance but the mileage drops off about 3 MPG on 87 vs 93 according to the DIC. I am running 87 now with it being so cold as it starts and runs much better on lower octane in the winter.

 

I will probably run 93 in my new truck when it gets here maybe not in the winter but I would not worry one bit should I or the wife forget and fill it with 87 (which has been known to happen on the Grand Prix) the PCM will compensate for it. How do you think the tuners can unlock the power they do? because the factory tunes are very very forgiving and very conservative.

 

I do have a bit of experience regarding engines/fuel systems I have been an ASE licensed tech for over 25 years, I am certified in advanced level drivabillity and have been to more seminars, classes and hands on workshops than I care to remember :crazy:

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

 

Octane booster adds 52 WHP and gives 7 extra mpg and guarantees the life of the engine to last at least 500,000 miles. It's a no brainier to use with every fill up. Same with blinker fluid and exhaust bearings.

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Thanks...that is good to know. I know my Vetted says premium is recommended, but not required. I just worry that if I ever had engine problems, and they could prove I had other than premium gas, they would have the perfect reason to deny a warranty claim based on manual instructions. Maybe one of the GM reps that monitor these forums could do some checking. I do, however, plan on using premium. In my Vette, I did some unofficial testing and found that the increased fuel cost for premium was offset by the increase in MPG by 2-3 mpg.

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Thanks...that is good to know. I know my Vette manual says premium is recommended, but not required. I just worry that if I ever had engine problems, and they could prove I had other than premium gas, they would have the perfect reason to deny a warranty claim based on manual instructions. Maybe one of the GM reps that monitor these forums could do some checking. I do, however, plan on using premium. In my Vette, I did some unofficial testing and found that the increased fuel cost for premium was offset by the increase in MPG by 2-3 mpg.

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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.

 

 

I was curious about this and went into the owners manual section on GMesi (the service information used by GM dealership techs) they update this continually on the fly so this should be the latest info. There aren't page numbers in the online version but here is the section under fuel. my guess is it replaced the wording you posted earlier. I highlighted the key info.

 

 

"If the vehicle has the 6.2L V8 engine (VIN Code J), use premium unleaded gasoline with a posted octane rating of 91 or higher. Regular unleaded gasoline rated at 87 octane or higher can be used, but acceleration could be reduced, and an audible knocking noise may be heard. If the octane is less than 87, a heavy knocking noise may be heard. If this occurs, use a gasoline rated at 87 octane or higher as soon as possible. Otherwise, the engine could be damaged. If heavy knocking is heard when using gasoline with a higher octane rating, the engine needs service."

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What octane and oil weight should I use?? Most common question I get asked on any vehicle working at a dealership. Why not just follow the engineers that designed it to be safe if your asking if using something else will damage it? And I don't ever suggest asking a saleman anything on a vehicle as they usually don't know much of anything period. lol :dunno:

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GM has been known to revise some of their recommendations. Plug gap and oil weight are two examples on Gen III/IV engines.

 

Also, GM provides the same specs to all owners with the same model. Some owners tow/haul all day, every day. Some only drive them to work and to soccer practices. While using the published GM specs is usually best, that doesn't mean it's always best.

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I would say this, if you ran 87 and was loaded down, during a hot summer month, and had detonation and continued to drive the truck and had engine damage I am sure GM would try to decline repairs and void the warranty.

 

So unless you have a extra $10k lying around why not just run the correct fuel? It is maybe $3-5 diff per tank, you can buy a $50k+ truck but yet skimp on the correct fuel.

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Given the verbage above, I don't think they could deny warranty for running 87 octane. 86 yes, but 87 no.

 

That said, any time you can hear audible knocking you are doing very bad things to the engine.

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i have a 2014 Denali with the 6.2 motor. i have driven the truck almost 10k miles. I can tell you that there is a big differance in the engines performance with using 92 octane fuel. i would use the higher octane fuel. I have averaged 19 mpg over the 10k miles. 80% highway and 20% city.

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It's pretty much how my 2011 5.0 Mustang I had worked. Ford recommended 91+ octane for full performance. However, you could use 87.

 

91+ octane: you get 420 horsepower and full performance.

 

87 octane: knock sensors would detect knock and would retard the timing. Horsepower would drop to 402. You would also have less torque.

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It's pretty much how my 2011 5.0 Mustang I had worked. Ford recommended 91+ octane for full performance. However, you could use 87.

 

91+ octane: you get 420 horsepower and full performance.

 

87 octane: knock sensors would detect knock and would retard the timing. Horsepower would drop to 402. You would also have less torque.

That's all I need to hear...PREMIUM for mine :thumbs: .

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