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6.2 Engine - Octane Requirements?

Whip

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Whip Enthusiast

Whip

Posted
Posted

I've been doing a lot of reading and like most of what I see about the new 6.2 engine. It seems the initial bugs with the 8 speed Tran are being worked out?

 

My question is on what type of fuel is needed in the 6.2. It seems everyone thinks that due to the high compression ratio minimum octane needed to run these things is 91. But the GM specs say that regular unleaded of E85 is recommended. So which is it?

 

I put quite a few miles on each year and tow a fair amount of time. 91 octane at my local station runs nearly .50 per gallon higher than 87 octane. Based on my miles driven and average overall MPG that's going to work out to about $900 more per year in added fuel costs. Add that to the higher initial cost of the engine and that's a pretty expensive upgrade. I like the idea of the increased power, but also like to know up front what it will cost me.

Jordan18 Enthusiast

Jordan18

Posted
Posted

Coming from my 2008 Sierra 5.3L, which I ran in the last months with 91 to see how the costs stacked up. Any increase in costs was actually offset by the improved mileage I am getting in my 15'. Where I was getting 16-17 mpg all the time, my new sierra with the 6.2L gets 22-23 mpg comparatively. I am happy to running 91 in this thing.

high country Enthusiast

high country

Posted
Posted

All 6.2's can not run e85, they are not flex fuel capable, they don't have the programming required to run it. GM says the 6.2 requires 91 octane minimum.

Roader Enthusiast

Roader

Posted
Posted

You can run lower octane than 91 but expect engine knock, especially at higher rpm and when towing

rmart Enthusiast

rmart

Posted
Posted

There are two manuals referencing fuel requirements for the 6.2L engine. Mine (built Feb 2014) says i must use high octane fuel. Others have manuals stating 87 is ok unless you hear pinging.

Whip Enthusiast

Whip

Posted
  • Author
Posted

Thanks for the replies. I was having trouble finding what I was looking for and came across this website called GMAuthority.com

http://gmauthority.com/blog/gm/gm-engines/l86/

 

If you follow the link you'll see they list specs for the 6.2 and specify regular unleaded or E85 as recommended fuel.

 

After reading replies here I did download the complete 2015 owners manual and of course you are correct - 91 octane.

 

It would be nice if GM themselves would be a little more forthcoming with that info. A shopper shouldn't need to download an owner's manual to find it. But I am happy to know it up front. Now I can make an informed decision to figure out how important that power is to me and how much I'm willing to pay to get it.

Thanks for the help!

Isriam Enthusiast

Isriam

Posted
Posted

The fuel lid says 91 octane recommended or required I forget. i ran 87 for years in two different 6.2's with no issues.

mdrew Enthusiast

mdrew

Posted
Posted

90 octane is all I can get where I live. I had to paste the lo spark table onto the hi on my Z06. I'm afraid to log the new truck with the 6.2......

galliher_nc Senior Enthusiast

galliher_nc

Posted
Posted

The fuel lid says 91 octane recommended or required I forget.

X2.

 

My truck says 'premium fuel recommended' right inside the fuel door.

mzodarg Senior Enthusiast

mzodarg

Posted
Posted

Coming from my 2008 Sierra 5.3L, which I ran in the last months with 91 to see how the costs stacked up. Any increase in costs was actually offset by the improved mileage I am getting in my 15'. Where I was getting 16-17 mpg all the time, my new sierra with the 6.2L gets 22-23 mpg comparatively. I am happy to running 91 in this thing.

Not Sure what rear differential you had on your 2008, but the 6.2 only comes with the 3.23 gears. my 2014 is tuned I run 91 octane and have 3.42 gears in the rear. In town I get on average 15.8 mpg and highway is similar to what you are reporting.

 

Just food for thought.

 

Mike

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