Shell gas

B6/7 S4/RS4
#1

This from a professional tuner specializing in Chevys. What do you guys think? I’ve never heard this.

I used to use it myself in my monte carlo SS… then after doing some data logging of my own car, I noticed a ton of knock retard… so I switched to Mobil 93, and it all virtually disappeared… and the thousands of tunes I’ve done for people, I can normally tell if they’re using Shell gas as well, due to all the knock retard in their logs… I’ll ask them about it, and they’re like - how did you know I was using shell!!! haha… so yep, I see it time and time again, shell gas causes knock retard issues… whatever additives they put in their fuel, causes issues… best to use mobil, exxon, sunoco, bp, chevron… mobil/exxon being the best to use…

#2

I think that the actual gas station turnover and location in the country is more important. I have seen multiple cars that filled up with old gas that was breaking down along with having water in it. It was pretty much required every time that we had a even remotely fuel related issue that technical assistance wanted to to take a fuel sample. Or pump some gas into a clear container and set it sit for a few hours to see if there was water in it that separated over time. Then there are only a few fuel refineries in the USA so the gas starts off the same for a wide area and then the individual branded stations add their additives to that basic stock. A NJ refinery had an issue with their fuel for like six months at one point and Audi tracked it down because all of the gas from multiple different stations was causing issues.

Then a little fuel system maintenance goes a long way too, just saying.

#3

Actually my curiosity was whether anyone had encountered the knock retard due to Shell gas.

#4

It’s interesting. My friend, who now has an E39 M5, used to have a MazdaSpeed3 which has a turbo 2.3. He said he only buys Shell gas and would never go to Chevron again because he had bad knock retard from Chevron fuel. So it may indeed be a regional problem, since it’s literally the opposite of what the statement in the original post says.

#5

Very interesting find! I only use shell 93… if you want me to do some logging, let me know and be happy to share. You might be onto something here.

#6

I would very much appreciate some logging. Thanks for the offer. I also use only Shell 93.

#7

PM me exactly what you need me to run. I also have access to another B6 S4. So I can do both while at it :wink:

#8

I don’t know exactly which measuring blocks, but it would be the ones related to timing. Hopefully one of the more cognizant members will chime in and tell us what numbers they are.

#9

I have logged before looking at my local shell and then my local Sunoco and Mobil gas station because I was convinced that Mobil gas was crap compaired to the other two and for me that was true. The Mobil gas appeared to have more knock but that was just one gas station I doubt they all are the same as Mobil gas is part of a few other gas companys that all use the same gas its just rebranded.

I kinda think the chevy tuner is full of it and that might be true local but not over the entire usa like jimmy was saying.

I would like to point out that gas stations are going to have different mixes of gas different times of year. Like in the winder you will see a winder blend of fuel. This will cause you to have a little more knock due to the fuel having additives in it to help on cold starts and cold mornings

Also depending on where you live and the local emission testing laws you will have additives that are different and mandated by your county or state. This means that California 91 is not as good as say NJ 91. I have driven across the country and found out that some states just have shitty gas and later did the research finding out what I have posted above and that’s that some states have additives they are mandated to add and some times of year you will see different blends.

So you need to take all that with a grain of salt and really keep that in mind when someone tells you this or that gas station is good or bad or not. From my experience and from the thoughts shared here

I think there is a lot more to the story as these two posts say as well. IMHO if you want to check brands of gas it needs to go way past just picking a station. You would IMHO really need to find out how good the turn over is as gas that sits attracts water and fuel with ethonal in it will attract 5x more water then standard fuel alone.

If you guys till want to tackle this. That’s fun and fine with me I just thought I would help add somethings to think about first. Let me know what blocks you guys are looking for

#10

Not being as familiar with VCDS as some, my curiosity is still if Shell gas causes that much timing retard.

#11

Don’t have B6/7 S4 or RS4, but I have seen this with Shell gas also on back to back tanks of Shell vs BP (warmer weather). Weather/DA were similar or within a few days of each other. Have tried it a few times to rule out a single gas station or any other anomaly. Have also tried with different Shell and BP stations. Saw it with the B8 S4 and most recently with the Golf R. I have heard this also about Shell gas from some guys around here also. Coincidence? Who knows.

#12

WOW ok interesting. There might be something to this.

#13

Thanks for chiming in tsivas27. Trying to find out whats up with this.

#14

I sent you a pm. let me know if you need help. I can walk you through what to do.

#15

justincredible if it’s logging procedure, I’d like to know as well so I can log my car too

#16

pm sent

#17

Weird, in Ontario, everyone swears by Shell 91 over everything else (for 91 obviously).

#18

I think it’s also due to Shell 91 being one of the few ethanol free choices here.
But as a result the lower octanes have more ethanol.

#19

Weird most local owners go for shell 91, over chevron 93 out here, mostly cause the 93 sits forever.

I’ll have to do some logging on this.

#20

Have any of you done any logging? I ask because I’m not able to do it myself. I have the VCDS, but also have my B6 dual mass flywheel trying to come apart, so my Avant is parked until I can find someone to do my chain guides, etc.
Thanks