So I filled my tank up 1/2 with 100 octane . Ran it down till the low fuel light came on. Then put 94 octane in from sunoco and toped it off with a full tank. I have gone through 1/4 of the tank and the 100 octane switch has not shut off on it's own like it normally does. So now that I know that I can mix the two when I get low and still keep the advance that the CPU does for 100 octane. So far I have 50 miles on the 94 octane. The exhaust no longer smells like the sweet 100 octane but it still performs like it.

Anyone else with 100 octane GMS3 try this?

 

Just be careful.. if the gas isnt what it supposed to be, things can go wrong by having too high of spark advance.

 

where in michigan did you get 100 ocatane from?

 

Speed way

#2290 880 E Maple Rd
Troy, MI
48083-2811
(248) 585-6414


If that is the case then the light will shut off and it will default to premium mode

 

Is it leaded?

 

no, unleaded $6.00 per gallon

 

dang 6 per gallon... lol

 

Wow... but hey man it must be fun.. lol..

 

Sounds like fun. Wish I knew where to get 100 octane besides the track. Would like to play with it before saying goodbye to my S3 PCM.

 

80 miles now and the light still has not shut off. Must have had more 100 in there then I thought

 

They have 100 turbo blue at citgo all around here but it's leaded. Runs good in my truck and sled

 

just an update 2 tanks after the 100 octane on 94octane and the light still has not gone off when I set it . Filling up on my third tank of 94 today

 

Well, if you haven't experienced any knock then it will continue to stay in 100 octane mode. I don't know just how aggressive GM made the timing advance on the S3 calibration, so just running 94 plus a little 100 maybe keeping your octane level high enough that you aren't experiencing knock and therefore can continue to run in 100 octane mode. I would guess that GM did some testing and after a certain point (25* typically) the car doesn't gain anymore from having advanced timing anyways so they just left it at that point and you just haven't hit the "magic octane" number that will cause knock yet.

 

leaded gas is good, its softer on the engine, better then unleaded

What is GMs3?

 

Hmm.. got a box of O2 sensors laying around?

GMS3 = GM Stage 3

 

x2

Plus I hope you are catless.