Yes 91, 93 when available. I tend towards Shell gas, sometimes mobil. I'm going to track my milage over the next couple tanks too.

 

Jim,
Any idea when the 2010 JKs can get the Flashpaq? I'm really jealous reading about how happy everyone is and I WANT ONE!

Thanks!
Erik

 

It doesn't matter which company you use, just the octane. All gas comes from the same refineries. They all have the same chemicals in them as well. Its just marketing that differentiates them. Sad but true.

 

Well sort of. All the gas (except Citgo, which has it's own south american refineries) do come from the same few refineries. Mostly in Texas, and along the Gulf.

However companies then add their blend of additives, making it "their own" I'm sure you've seen all the advertisements every time you fill up "BP gas now with IQ" wtf is that?
Anyway, I have no proof what so ever, other then my butt meter, but I swear Shell gas gives me the most power. I'd rather BP, because I have stock in them.... But I can't argue with my butt.

 

Actually, its the same additives as well. A friend of mine's wife worked at the refinery and told me its all the same. Of course it's just her word, but I have no reason to not believe it.

 

Does the programer void the factory warrenty? Just curious

 

It's academic because you should always program it back to stop before taking it to the dealer for warranty work.

If you burned a whole in a piston from running to lean due to a programmer, the dealer could probably figure it out or maybe not , if the PCM stores a history.

 

Hey I'm not trying to be argumentative..

My neighbor is a chemical engineering professor at Washington University. (is supposed to be one of the top schools in the county as their fond of saying) and we talked about the additives being the only difference.

 

Sorry I didn't see this earlier, but I've been real busy at work. Changing the tune in cold weather shouldn't make a difference. The AIT sensor is part of the loop with air/fuel mixture and changing tunes isn't going to affect it's role.

The big thing with winter fuel mileage is really getting up to operating temperature which is often pretty hard to do with below freezing temperatures. Additional air density draws more fuel, and lower temperatures keeps the fuel mixture richer for a longer amount of time. Then for those with automatics, it takes longer for the torque converter to lock up. In all it's easily conceivable to see a 10-15% hit in mileage during the winter months, which for me says that I'm going with low octane settings on my programmer.

Oh and one last thing, the winter gas thing is totally a myth and the fuel your putting into the tank in the winter months has nothing to do with the decrease in mileage you may experience.

 

Funny, the wife seized my cap immediately as well and it's definitely pretty sporty.

I'm still waiting for Ron Rapp to send me a six pack though for all the tech support that didn't get to his desk.