Are you still using premium gas?

Z45 · June 12, 2022

Quote

For high-performance vehicles that require premium fuel (91 octane or higher), fuels of at least this octane must be used. Using lower octane fuel may result in reduced performance, knocking, and/or permanent engine damage that is not covered under the terms of the New Vehicle Limited Warranty. Using higher octane fuels in a vehicle that only requires regular unleaded fuel will not increase performance or improve gas mileage. Only use the octane-rated fuel recommended as specified in the vehicle’s Owner’s Manual.

per GM Service info

zelmo · June 12, 2022

This is exactly what the manual says:

Recommended Fuel (6.2L
V8 Engine)

Premium unleaded gasoline
meeting ASTM specification D4814
with a posted octane rating of 93 —
(R+M)/2 — is highly recommended
for best performance and fuel
economy. Unleaded gasoline with
an octane rated as low as 87 can be
used. Using unleaded gasoline
rated below 93 octane, however, will
lead to reduced acceleration and
fuel economy. If knocking occurs,
use a gasoline rated at 93 octane
as soon as possible, otherwise, the
engine could be damaged. If heavy
knocking is heard when using
gasoline with a 93 octane rating, the
engine needs service.

Nothing is said about a warranty claim being denied by using 87 octane. Obviously performance will not be as good as using 93 octane but if you are not putting a heavy load on the engine and there isn't any knocking I don't see what the problem is. BTW - my C7 says the same thing about the 6.2L in it. I does say to use at least 91 octane in the supercharged version.

TNTSierra · June 12, 2022

I bought a 6.2L for the power and performance. I have used 91+ octane in it from day one. It has 40k on it now and still turns the new tires I put

on it Friday like it did from day one! Yes premium does cost more but I’d rather put what is recommended in it as a piece of mind knowing I’ll be fine driving down the interstate or highway with my family. Those that choose not to use premium is absolutely your choice but then you probably should have just gone with the 5.3L then!

Edited June 12, 2022 by TNTSilverado

swathdiver · June 12, 2022

So Zelmo, why don't you prove us wrong? Get an ODBII adapter and use the Torque App or something similar on your phone and set it up to record a drive with 87 and post it to youtube and link it here.

pokismoki · June 12, 2022

if your cheap and want to run 87, i would highly recommend you install the 175 thermostat to keep your KR as low as possible

what's crazy when I lurk on the HPtuners forum and I'm astounded that pro tuners and enthusiast are tuning thier cars with the high temp thermostats, looking at their tune files, they have water temps pushing 235 F, at idle. WOT who knows what the heads are seeing probably 250-260F. while the puters is pulling KR. some guys have no clue. just keep pouring fuel on it

cost for HP/$$$, the colder thermostat makes the most power of any speed part on the market

Edited June 12, 2022 by pokismoki

John813 · June 12, 2022

Only use 93.

pokismoki · June 13, 2022

anyone play with 101LL AV gas, I always liked the smell when catless

zelmo · June 13, 2022

16 hours ago, swathdiver said:

So Zelmo, why don't you prove us wrong? Get an ODBII adapter and use the Torque App or something similar on your phone and set it up to record a drive with 87 and post it to youtube and link it here.

I don't need to prove you wrong. Instead I am going to follow GM's guidance which is that 87 octane is acceptable if you are willing to give up some performance. When the spread is reasonable I will use 93 and when it is not I will use 87 or 91.

As for the idea that I should have chosen the 5.3L that wasn't an option for the truck that I wanted. Additionally, that was before Brandon was elected and declared war on the oil and gas industry.

Gangly · June 13, 2022

On 6/11/2022 at 12:40 PM, Wiggums said:

I use premium gas in mine since I leave it parked for weeks. I don't think I've filled up in three months.

You might want to consider STABIL, lol

Gangly · June 13, 2022

On 6/11/2022 at 6:03 PM, swathdiver said:

They do, it is not speculation, those of us who pay attention have witnessed it.

Your high compression engines knock/ping while driving around town on that 87 swill. You cannot hear it. You take off from a light, the motor knocks and the computer pulls timing. You go to pass a guy, even without downshifting, the motor knocks and the computer pulls timing. 1000 more times on your trip to the mall and back. You don't think that will take toll day after day, month after month, year after year?

I don't know more than everyone else, I paid attention and learned it here. You can too if you do your research.

Last time at the drags I took a video from inside the cab, from the stands and took a Snapshot with my Tech-2 to show you guys that the motors do knock and you cannot always hear it. I am not tech savvy enough put three videos into one but someday my kids might slow down and help me post it for y'all.

Myself and others have posted videos from youtube of 6.2s that came apart because of prolonged use of low octane gasoline.

EVERY motor experiences knock under load, regardless of fuel type, but lower octane fuel will create knock more consistently when used under load on higher compression engines. Under normal driving conditions it is minimal, but the race track is NOT normal conditions. Also, knock rarely affects rings but generally pistons, plugs and valves can wear under SEVERE long term usage.

A .4 difference in compression ratio is not a lot (load wise), and GM states in the owners manual that it is acceptable to use 87 octane in the 6.2. You are free to believe what you want, as others are free to believe what they want, but don't grab a pitchfork and start talking high and mighty when somebody disagrees with you, especially when the engineers who designed the system condone the use of 87 octane.

Wiggums · June 13, 2022

5 hours ago, Gangly said:

You might want to consider STABIL, lol

My mechanic said to use that if I don't refuel in over six months. For now, it's been three months when I refuel so.. no need.

swathdiver · June 13, 2022

12 hours ago, zelmo said:

I don't need to prove you wrong. Instead...

I figured as much.

9 hours ago, Gangly said:

EVERY motor experiences knock under load, regardless of fuel type, but lower octane fuel will create knock more consistently when used under load on higher compression engines. Under normal driving conditions it is minimal, but the race track is NOT normal conditions. Also, knock rarely affects rings but generally pistons, plugs and valves can wear under SEVERE long term usage.

A .4 difference in compression ratio is not a lot (load wise), and GM states in the owners manual that it is acceptable to use 87 octane in the 6.2. You are free to believe what you want, as others are free to believe what they want, but don't grab a pitchfork and start talking high and mighty when somebody disagrees with you, especially when the engineers who designed the system condone the use of 87 octane.

When my motor is burning E85 it does not experience any knock, not even at the drag strip.

I am sharing with people what I have learned from these forums and through my own observations with advanced scan tools. The engines knock/ping on 87 and it does indeed damage them over the long haul.

Myself and others have posted the videos of teardowns showing the damage done, rings and pistons.

I have a 6.2 but am not fool enough to burn 87 in an 10.5:1 motor. Our 5.3 with its 9.95:1 compression drinks 93 also.

That's why I challenged the proponents of low octane gas in a performance engine to prove me wrong. Not too proud to admit when wrong. Instead of taking me up and verifying my claims, they run back to the owner's manual without reading carefully what was written.

zelmo · June 14, 2022

11 hours ago, swathdiver said:

I figured as much.

When my motor is burning E85 it does not experience any knock, not even at the drag strip.

I am sharing with people what I have learned from these forums and through my own observations with advanced scan tools. The engines knock/ping on 87 and it does indeed damage them over the long haul.

Myself and others have posted the videos of teardowns showing the damage done, rings and pistons.

I have a 6.2 but am not fool enough to burn 87 in an 10.5:1 motor. Our 5.3 with its 9.95:1 compression drinks 93 also.

That's why I challenged the proponents of low octane gas in a performance engine to prove me wrong. Not too proud to admit when wrong. Instead of taking me up and verifying my claims, they run back to the owner's manual without reading carefully what was written.

So you know more than the engineers who designed the motors and specified the fuel? Instead of asking anyone to prove why you are wrong YOU should prove that you are right instead of those engineers. Don't give me some BS that at some point you or someone else posted a video. Post it now and be sure to give accurate information regarding how the motor had been run.

shakenfake · June 14, 2022

Lol @zelmo

Gangly · June 14, 2022

14 hours ago, swathdiver said:

When my motor is burning E85 it does not experience any knock, not even at the drag strip.

I have a 6.2 but am not fool enough to burn 87 in an 10.5:1 motor. Our 5.3 with its 9.95:1 compression drinks 93 also.

Instead of taking me up and verifying my claims, they run back to the owner's manual without reading carefully what was written.

If you have no knock running E85, then why don't you run it year round, every tank? I guess some knock is acceptable, or is it that you don't want to pay so much? Which is it, because either answer will contradict your opinions on the matter?

You do realize the 5.3 L84 runs at 11.1:1 and that GM's recommended fuel grade for that motor is 87 octane correct? Basing octane level on compression alone is poor science when dealing with modern DI engines. Modern DI motors are able to control fuel release much more accurately/timely than traditional FI or carb'd engines, and for that reason they are able to run lower octane fuels without detonation (knock) that could potentially damage the the piston, valves, plugs, etc.

It's good that you are collecting data from you and your friends experiences, after all its the third step in the scientific process that allows for the logical procession of recognizing a need all the way through determining a conclusion, but that's also where your lacking. You and your buddies track information is nice to have, but your basing your findings and conclusions on one data set and have excluded extremely important variables such as heat transfer/thermodynamics, typical engine usage, etc..

Regardless, you are free to believe what you want and do what you want with your vehicle, its yours to do so with. However, try not to tell others what they should do with theirs and then try to brow beat them based on your beliefs. Its a bad look.

I am finished with this discussion, but I still hope you have a great day and enjoy your 6.2 Silverado.

Edited June 14, 2022 by Gangly