91 octane fuel

[VT2500HD]

I recently purchased a 2004 chevy 2500 HD with 6 liter motor, it is equipped with some obvious aftermarket items such as JBA headers and exhaust, and Vararam cold air intake. then there is a note on inside fuel door that says minimum 91 octane gas only. I am wondering if there is any way to determine if there was a tune of some sort installed on the truck that requires 91 octane fuel? Thanks for any help.

[HEMICAT]

Sheese, my 2012 is supposed to use 87!

[yukon25008.1]

depends on the truck..I have a raylar cam in my 8.1 and ray from the company told me the big blocks like lower octane so 87 is wgat im tuned for and what i run..

you want to see a real good change or result.. go buy a bottle or 2 of startron fuel additive and/ check my post about it..The stuff is great and will instantly make your truck run right,better, and pick up 1-3 mpg,s

Contact blackbear for a custom tune, justin is the best with these gm motors.. you will see a general improvment, in idle,mpg,smoothness, and more power and TQ increase then any handheld tuner will ever make.

the 6.0 sierra i had never seemed to run any different on 87,89 or 93...buty i wasnt tuned either

[yukon25008.1]

with the stock tune or configueration on the 6.0 ive never had or heard of anyone having a knock.. but i guess its possible,

[HEMICAT]

I've noticed no difference running a higher grade so I'll save my money!

[Portdriver]

The 6.0L runs best on 89+ octane (91 is optimum). This is a well known fact. They will knock a lot if you run 87.

 

 

+1 - My 2011 6.0 knocks running 87.

[Prokopchuk_9]

The 6.0L runs best on 89+ octane (91 is optimum). This is a well known fact. They will knock a lot if you run 87.

 

You sir are correct. I data logged mine running 87 vs 91 it pinged WAY more on 87. In fact I was able to bump up my timing enough to gain a solid 1.5-2 mpg across the board. Running 91 is very much so "worth it" if you have it set up properly.

[HEMICAT]

Ha! LOL! I guess I'm just lucky!

[Prokopchuk_9]

Ha! LOL! I guess I'm just lucky!

 

Not really a matter of luck, depends where you're gettin ur fuel too. They're is a few different factors that make your truck ping but I wouldn't waste cash on 91 if the vehicle wasn't tuned for it either. It has benefits but only real

Benefits are with tuning...IMO.

[HEMICAT]

For sure! Yeah the stations with the ethanol probably don't help. Also I think some stations' low grade is 89.

And mine definately isn't tuned- no way! It will absolutely shred tires now on dry pavement, and that's good enough for me!

[sonjaab]

My 07 gmt-900 6.0 runs 87 w/15% ethanol blend gas we have here in NY

and runs fine.