6.2L fuel requirements; tunes?

Chance Neel · February 18, 2017

I just registered the myGMC app and selected the 6.2L engine where it states that 87 octane is capable of being used.

Fuel (Gasoline - L86 6.2L Engine)

Object ID: 4196747

Premium Recommended Fuel

Use premium 93 octane unleaded gasoline in your vehicle. Unleaded gasoline with an octane rating as low as 87 may be used, but it will reduce performance and fuel economy. See Fuel in the owner manual.

On another note. I live in Houston are there any shops that do custom tuning? Does custom tuning ruin the warranty or are there ways around that? Are there still issues with tuning the 8 speed tranny and also does AFM help or hurt? At 65mph on pretty flat terrain it doesn't kick on yet so not sure what it takes to really make it worthwhile. And why doesn't AFM kick on when idling and not under load?

hurricanoday · February 18, 2017

N0 it has always said that. Are you missing the first part where is says Use premium 93 octane in your vehicle? "capable" meaning it will lose power and mpg

Chance Neel · February 18, 2017

N0 it has always said that. Are you missing the first part where is says Use premium 93 octane in your vehicle? "capable" meaning it will lose power and mpg

no I can read just fine. Just like where it says 87 octane can be used. Before buying I had only found threads where people asked if they could put 87 in. People said 93 was required and less would cause pinging. There's a big difference between those statements and what the app says. Saying you can use 87 octane is something I hadn't come across while reading. Hence why I asked if it was a recent change meaning if there were changes in the software/design or if it was just people's opinions. It's right there in the same sentence so before stopping after the first line keep reading. It won't hurt.

hurricanoday · February 18, 2017

Seems pretty cut and dry to me, 93 is recommended but the truck will run on 87 with reduced performance and fuel economy. I would say pinging would be in the reduced performance category. It has always stated 87 can be used with the negative effects listed.

I wasn't trying to be rude, just wasn't sure if you were understanding. You can put what ever you want in your truck. So to answer your question no it hasn't changed

Lgetz · February 18, 2017

Texan you can use 87 octane fuel but the truck will pull timing and cost you power. I would not do a custom tune because if you have a problem with engine or transmission the dealer needs to send screen shots to GM regional before doing work. They can tell a tune was installed and do a powertrain warranty block. AFM should function normally under the scenario you describe. Even with my mods AFM works up to about 72-74 mph. Around town I keep transmission in M7 to turn off V4 mode. With my exhaust it makes a chopper sound around 35-47 mph in V4.

Edit below:

I have always filled with 93 octane mostly Exxon gas. On one occasion a buddy borrowed my truck and filled with 87 octane. It was pinging bad under moderate throttle.

Chance Neel · February 18, 2017

I don't plan on doing so but saw that and wondered if there were changes to the motor this year that I hadn't known about since I had only read it wasn't to be done. As far as AFM goes I just bought it earlier with 6 miles on it and drove it about 60 miles home with 65 on the cruise control. I never saw it hit AFM mode unless it was a slight grade reduction. I've never had a tune done on a gas, just my Ecodiesel, so didn't know if you could just flash it back before going in or what.

Sierra706 · February 18, 2017

I don't plan on doing so but saw that and wondered if there were changes to the motor this year that I hadn't known about since I had only read it wasn't to be done. As far as AFM goes I just bought it earlier with 6 miles on it and drove it about 60 miles home with 65 on the cruise control. I never saw it hit AFM mode unless it was a slight grade reduction. I've never had a tune done on a gas, just my Ecodiesel, so didn't know if you could just flash it back before going in or what.

Afm doesn't activate as much using cruise control due to it being less efficient than your foot and reasonable throttle inputs on anything but flat land.

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Krusty · February 18, 2017

I don't plan on doing so but saw that and wondered if there were changes to the motor this year that I hadn't known about since I had only read it wasn't to be done. As far as AFM goes I just bought it earlier with 6 miles on it and drove it about 60 miles home with 65 on the cruise control. I never saw it hit AFM mode unless it was a slight grade reduction. I've never had a tune done on a gas, just my Ecodiesel, so didn't know if you could just flash it back before going in or what.

No cruise control for the first 500 miles - read your manual on break-in........ Page 267..........

Chance Neel · February 18, 2017

No cruise control for the first 500 miles - read your manual on break-in........ Page 267..........

it was late when I got it! And I asked at the dealership about break in and they said nothing required.

Diver6 · February 18, 2017

On occasion ill run 87 in mine if I know i'm not towing and haven't noticed any bad side affects from it but I always run 91 when towing, As for the AFM mine kicks in a lot even on cruise contol running 65, I can't tell unless I see it on the DIC but I still have factory exhaust so far.

ewiski · February 18, 2017

So your spending the extra money for a 6.2 and then wont run the proper fuel in it?

Cowpie · February 18, 2017

I would probably try an experiment with mid grade 89 if one wanted to see how that worked. Not so sure I would opt for 87 simply because of the compression ratio and the timing cycles the ECM goes thru to determine correct timing for the fuel being used. Seems 87 would cause a lot of knock events as the ECM tries to keep timing correct for the fuel. The ECM repeats these cycles as the vehicle is driven. It will advance timing till a knock event occurs then back it off. Then it will go thru the cycle again. With 87, this would be going on all the time. 89 maybe.

Dnt · February 18, 2017

I have run several tanks of Shell regular 87 octane without any pinging or noticeable power lose but most of the time I run the Shell V-Power Nitro+ premium 91 octane. Mainly because the name is cool, I mean how can you go wrong with a name like V-Power Nitro LOL that is some marketing right there boy. This super fuel is probably what makes my gas mileage so good?

Krusty · February 18, 2017

I have run several tanks of Shell regular 87 octane without any pinging or noticeable power lose but most of the time I run the Shell V-Power Nitro+ premium 91 octane. Mainly because the name is cool, I mean how can you go wrong with a name like V-Power Nitro LOL that is some marketing right there boy. This super fuel is probably what makes my gas mileage so good?

I wouldn't believe the DIC - always hand calc. And you are not always going to be able to hear the pinging.......