[Knobs]

I've searched the site, and the threads found discussing premium vs regular in the Chevy 6.2l V8 are quite old.

The specs I've found online say this engine has a compression ratio of 11.5:1, which in the "old days" would mean premium fuel.

My owner's 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.

(underlining is mine)

I've experimented with regular gas for a recent trip with my truck, and did not notice any issues.

I assume the engine control is adjusting the timing.

I didn't time any 93 vs 87 acceleration numbers, but I noticed no (obvious) power reduction and the gas mileage (calculated by the truck - I did not verify) did not materially change (it is still in the vicinity of 20 mpg for highway cruising @ 65 mph).

Does anyone else here run regular gas with this engine?

 

[Denali69]

Per GM................
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.

I have owned a GMC with 6.2L engine since 2012 and I never resorted to anything less that 91 which is the norm in this area. I suppose if you plan to trade it in every so many years, let the next owner deal with any engine damage that could result from long term use of low octane fuel.

 

[Knobs]

Per GM................
... Only use the octane-rated fuel recommended as specified in the vehicle’s Owner’s Manual.
...

Please see my quote from the owner's manual for my truck in my OP.

Here it is again:

"Unleaded gasoline with an octane rated as low as 87 can be used."

My question wasn't about what was permitted by GM - I already knew 87 octane was permitted; I was wondering if using 93 octane had any real measurable benefits (other than making my wallet thinner).

 

[RayVoy]

I think what Mike was trying to say was: yes you can use 87; but the engine will knock. Spark knock will burn holes into the top of the pistons.
This isn't as big a problem as it once was, today's trucks have computers that will dial back the spark timing and let the engine operate with a lower possibility of knocking.
And I know you know that.

What Mike was trying to point out was that yes the computer will retard the timing when the knock sensors hear knocking; but, the knock has to have occured before the computer changes the timing. You may not hear it, or feel it; but a knock has occured

And, how often will the process repeat? i don't know, I'm sure it's a number of times in a driving cycle. Maybe the program locks down the timing after a set number of occurrences per drive; I don't know what the program specs are.

But at any rate, using 87 gas will cause knocking that you do not want to have.

Your gas is cheaper than Canadian gas; but even up here the extra cost is worth it in my opinion.

 

[Denali69]

What I posted came right from GM so take it up with them if you disagree. Your owners manual says premium fuel is "highly recommended". Note, engine damage from not using the recommended octane could be subject for warranty denial.

Here► Optimizing Fuel Economy with Top Tier Gasoline

 

[Knobs]

What I posted came right from GM so take it up with them if you disagree. Your owners manual says premium fuel is "highly recommended". Note, engine damage from not using the recommended octane could be subject for warranty denial.

Here► Optimizing Fuel Economy with Top Tier Gasoline

They won't deny a warranty claim for using a fuel they say is OK to use.

Again, my question is not whether or not I have GM's blessing (my owner's manual says I do), but whether using premium fuel make a measurable difference in fuel economy or power.

 

[RayVoy]

I think I'm done with this topic