Premium in a 5.3?

[kstruckcountry]

Wolf Creek, Bert, and I70 are the climbs I do the most.

 

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[Jon A]

Guys, altitude doesn't save you with these engines the way it would with the older engines with much more simplistic tuning/timing adjustments. Altitude largely doesn't matter with the new engines. The timing maps are based upon cylinder airmass vs. RPM--if you get knock on whatever octane at a certain spot in the map at sea level, you will get knock at that same spot with that same octane at high altitude--the only difference is you'll need a slightly larger throttle opening to get there.

 

The big difference with altitude is WOT--you'll no longer be able to physically reach the "top of the map" so to speak, meaning at WOT you'll be at a lower line on the map. If that part of the map is tuned properly, you'll see no difference with respect to knock vs. octane no matter your altitude.

 

For a real world example, with my 6.2 I'm running significantly retarded timing throughout much of the map largely because across most of Montana 91 octane is the best I can get. Timing that is fine with 92 octane at sea level gives tons of knock on 91 octane, even at 5000'.

[rreale]

i run 87 in mine.

i run 87 in my 13 camaro SS, no problems. and thats what the manual calls for.

 

I ran 87 once in my 2002 Camaro Z28....it didnt like knocked a little

 

 

premium fuel is SOOO pricey nowadays. used to pay 15-20 cents above the 87 price. not its 40-50 cents above 87 where i live

[Colossus]

Costco isn't too bad.. Plus it is top tier now.

[diyer2]

Costco gas prices.

Rounded to the next penny.

Reg. $1.86

Prem. $2.26

[Aaron1085]

 

 

Yes, indeed. At higher elevations on naturally aspirated engines, less octane is required to prevent knock. Hence, why you see 85 octane around the front range and the hill country of Colorado.

 

But knock is caused by a number of things. Carbon buildup on pistons can cause it, by elevating the compression a little. A stock engine that is in good shape and designed for 87 should do just fine on 87. If there is a need to use higher octane to overcome knock, that is the sign of another problem, not the fuel.

 

I am not in the Seafoam camp, but I do like Techron, Amsoil P.I., or Schaeffer Neutra added to the fuel every couple thousand miles to reduce carbon and other buildup.

Techron, amsoil PI...? Input on these over the basic seafoam?

 

 

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[diyer2]

I'm not a chemist but Seafoam is what I use. I use it as a fuel stabilizer, fuel system cleaner, carbon remover. No complaints.

I believe this choice is similar to what oil you like.

[Cowpie]

Techron, Amsoil P.I., Gumout Regane, CRC Intake Valve Cleaner and some others have PEA (Polyether Amine) is the primary ingredient in these. PEA is well accepted as one of the best agents for cleaning intake systems. It dissolves carbon quite effectively without the risk of having particles large enough to damage valves and such.

[diyer2]

Good info cowpie.

I have been using Chevron Techron in this truck since seeing it mentioned on here.

[Dixon700]

Costco gas prices.

Rounded to the next penny.

Reg. $1.86

Prem. $2.26

 

The cheapest I've seen regular around here that I've seen is $2.25 for regular, and there is no Costco anywhere near here.

For fuel additive I run startron with a mixture of Walmart brand injector cleaner or gumout, or techron if they're on sale. I've never ran anything above 87 octane in any of my cars or trucks. I even run 87 in my quad that calls for 91+ octane and it's never had any knock.

[6sigma]

Resurrecting an old post here. Came looking for this info after I tried a tank of mid-grade 89 octane in my 17 5.3 and was amazed at how much better it ran than the 87 octane. I've since tried some 93 octane and it runs about the same as 89, so I think I've settled on mid-grade as the best bang for the buck. 

 

I've followed the age old advice that there is nothing to be gained by running higher octane than what the factory requires, but that is different now with Direct Injection. DI allows the computer to manage both spark AND fuel injection timing. DI allows a relatively high compression engine like the 5.3 (11:1) to safely run 87 octane, because the computer can retard spark timing and also delay fuel injection to better manage knock. So while 87 octane won't hurt the engine, higher octanes do allow the engine to improve power and run smoother. 

 

I've noticed that 89+ octane also allows the engine to run with more throttle at lower RPMs. The truck downshifts much less, where with 87 octane if you breathed on the gas it would want to downshift. It would do that to avoid low RPM load, another knock management technique.   

[Loco-diablo]

I run 89 exclusively in my 2017 5.3L


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[GMcD]

Ive been running 93 just because Costco only has 87 or 93. 93 also seems to be about 40 cents cheaper a gallon than at regular gas stations.

[J.Wilhelm]

Also noticed a better running and responsive 5.3L after installing the 89+ octane mod. 

[Daly]

I've only ever run 91 or higher in my vehicles. The 91 runs better on it and the Duster was built to run on it. And I just run it in the 17 because...