I've heard of a few people getting shockingly high levels of knock counts these days on cars that were tuned 6 months ago and ran fine, and I am now wondering if it has something to do with the reformulation of shell's and bp's gas. Shell now uses nitrogen in their gas as a cleaning additive, and bp has added something called "invigorate," and I wonder if this has hurt octane ratings/detonation resistance. Anyone who is experiencing these newfound knock counts care to chime in with what brand of gas they use? If the responses are all the same, then maybe some light can be shed on this mysterious new problem.

 

ill use pretty much anything 93 (bp, mobile mostly) but i refuse to use sunoco. Sunoco used to be the only station i would fill up with up until i had 3 separate problems with them.

First i had a sunoco employee try to rip me off for $20 bucks in gas credit becase he entered it as 91. I refused since at the time my audi was tuned for 93 only.

one time in northern PA i got bad gas in which all my sensors came on, i got a check engine light and had to drive out of boost to avoid knocking until the gas tank was empty.

same thing happened when i was down in MD, i got bad gas from sunoco again. all sensors and check engine lights, had to drain the tank and wast 70 bucks.

i agree most bad gas is due to old tanks or getting the last of whats left, but after i had that happen twice, and my buddy had that happen as well with sunoco in a different third state, I try to just avoind sunoco all together

 

Chevron and Shell only for me! I used to use 76 cuz I got it free and it was always fine.

 

Agreed..

Nitrogen is inert... hows that help combustion?

 

I always use shell.

 

I never said it helped combustion? They use/advertise it as a cleaning agent.

 

Only Shell or Sunoco 93 in my VIII. If I use something else Mr. knock light gets happy

Funny how 93 is not 93 everywhere. Ethanol content likely has something to do with it but i'm no fuel engineer so F it. I'll just stick with what works

 

it may be in my head but i feel like i get more bang (not knock) with sunoco 93. the car pulls quicker and harder. and my gas mileage is a lot better than with shell 93.

 

93 bp/shell/exxon & a little toluene helps to keep the knock away

 

This is a total moot point.. They all use the same gas, No ones is better than the others. Countless shows and articles have been written about the fact that gas comes from the same place. Mobile doesn't use mobiles gas. It basically goes to the refineries, all the gas travels down pipelines from the different refineries and mix together. The only difference comes at the end...Very few places add a few detergents..and from what I've seen, it's at such a high dilution rate, it doesn't do anything. They market the crap out of it and basically give people the placebo effect.

Just google "gas comes from the same place" or different variations of..

 

In ohio there are only two choices the best being sunoco 94 and then shell 93

 

I read a post from mellon somewhere, that his car ran better with the 10% mix. Think it was from BP.

 

Putting Texaco, Enrite, Valero, or Lucoil in my car and it'll beg to differ. Might all come from the same place but what ever Shell and Sunoco add in my area keeps the knock at bay

 

Since Hess is somewhat cheaper locally and the closest station to my house I usually fill up there. I used to always go to Sunoco when they had 94 octane but now that they dropped that slightly higher octane I see no reason to spend 20 cents more per gallon.

I'm pretty sure the 10% enthanol blend that is placed into the gas will somewhat lean things out and give you worse gas mileage compared to gas without ethanol, but luckily if you tune your own car it's a minimal difference.

http://en.wikipedia.org/wiki/E10_fuel

http://en.wikipedia.org/wiki/Octane_rating

Lots of info on that page!

 

Shell or BP in Chicago