I know my Vette pretty well, I know how it's supposed to sound, how it feels when you drive, whether it's responding right when you accelerate and so on. It's an 02 w/77K, So over the last month or so I have been getting some weird noise under moderate acceleration, couldn't quite put my finger on it but it sounded like a loose pulley or belt or almost like it was about to start knocking and it has slowly gotten worse. I was going to bring it in for service and have this checked when it dawned on me that it may be the gas. Over the years I've beeen using BP or Gulf gas, always Premium and the car has always run good but after learning about top teir gas I switched to Mobil. So for the last few months I've been filling up at the same Mobil station that is next to where I work. So just to eliminate the gas theory I ran it down to less than 1/4 tank and filled up with BP 93. About halfway into my drive home the sound slowly started to disappear and by the time I got home the noise was gone and the car felt noticibly better, more responsive. I'm convinced that I've been paying for 93 and getting 87 at the Mobil station, needless to say I can't prove it nor am I the type of person to make a federal case out of it, I just won't ever get gas there again. It seems improbable in this day and age a national chain gas station would be pulling a switch on the gas grades or maybe they just hooked up the delivery truck to the wrong tanks on their fuel delivery, who knows. All I know is that my car is back to sounding and driving normally. Just though I would share this and see if anyone else has experienced this.

 

May not be that they have regular instead of premium in the tanks, but could be some other contaminates that are degrading the quality of the gas. Hard to tell without an analysis of the gas though. If it runs better on BP gas, I'd stick with that.

 

I find that the cars that I have ever driven have run differently depending on the brand of gas that I put in them. There are brands of gasoline that I just won't buy because of the inferior performance that I believe they deliver.

Ironically, I never buy Esso gas, here in Canada. Esso brand is sold at stations operated by Imperial Oil Ltd. Canada, which is 69.8% owned by ExxonMobil.

However, I do insist on Sunoco brand gasoline any grade; available both in Canada and over the river in the U.S. Ultra 94 is the name of their premium grade here in Canada (Ultra 93 in the states). 94 octane, booyah! Cars run very well whenever I use it.

 

If I don't have at least 91 octane in my 04, it knocks. 91 octane is about all you can get here and I never ever run ethanol.

 

Its almost impossible to really know what you are getting.

If the last guy bought 87, and you select 93 - or 94 where available - you dont know how much of 87 is in the lines before it starts pumping your selection.

I cant remember the last time I found a Sunoco Ultra only pump.

Also, running 87 in a C5 should not cause any problem or strange sounds (unless you have a aggressive aftermarket tune). The stock ECM should be able to adjust to the lower octane. There will be less throttle response and WOT power. Knocking is usually more of an issue of bad gas, not just lower octane.

 

I'm not sure I understand you. You started with saying you almost always use BP or Gulf, but always premium. And that only recently used a Mobil station near your office. You go on to state you ran the tank down to 1/4 and refilled with BP premium. And only then you felt to improvement in operation. ( Isn't that the fuel you just said was giving you trouble ?) And that you'd stay away from Mobil gasoline. So I'm confused which gas was giving you problems, the BP, Gulf or the recently used Mobil ?

But overall, and in the most recent years Gasoline quality has plummeted. And with the addition of 10% ethanol it didn't get any better, (And it will soon be 15 or 20% ethanol) if the EPA gets it's way. But it's very difficult finding any gasoline that isn't contaminate or mixed with another grade. It's like anything else today, you get a smaller or poor quality product for 25% increase in it's price. You can't win !

 

My car ran lousy on the Mobil gas, and quickly felt an improvement after going back to BP. The kicker is Mobil is always about 10 cents more per gal than BP, but I didnt mind beacause of the top teir rating, I thought I was getting a better quality fuel. Perhaps the Mobil station got their tanks crossed or maybe my car just likes BP better, Anyway I'm gonna stick to what my car runs better on. I was just curious if anyone else had noticable differences in their cars with different gas of the same grade.

 

OK, Now I see what you mean. Down here outside Philly, I use Exxon-Mobil with good results, but I manly stick to Shell V93 octane. It's without a doubt the most purest gasoline I've bought in a long time. But as i mentioned, gasoline is getting harder to find a good grade. I wish the government would stick to the real problems we have. Cars today run 99.9% cleaner that anything built in the late seventies or eighties.

 

One of the things you might consider is the station itself, I try to only use very busy stations that are on routes that have a lot of traffic going through them.
I'm always suspicious of slower paced gas stations and how long that super has been sitting in their tanks, there are less cars using super today, and with the economy being what it is, and gas prices being what they are, less people spending extra for higher octane fuel.
The only things using super today are the higher end cars and bikes, so not a lot of turnover in the less busier local stations equals skunky gas.
Not to mention the Ethanol crap.

 

I had this problem too. I attended the HotRod Magazine PowerTour this last June and it seemed like the farther away from the gulf I got, the worse the quality of gas got. I read an article about gasoline quality in different areas of the country and I'm glad I live in Texas.
I also ride a Yamaha R1(crotch rocket for those who don't know) and with a cr of 12.4:1 it's very noticable when I get a bad tank. Just fill up at the top tier stations in high traffic areas.

 

I have not run anything but regular, included wal-mart, HEB, fina, QT, don't like the shell with no ethenol as it pings sometimes in my wife's avalon. by the way this is in my 03 zo6....not giving anymore money to gas thieves than I have to and I don't mean the stations or arabs. flame suit on so go for it...lol

 

When i lived in texas I always got a kick out of watching the tanker trucks line up at the refinery. What's funny about that? Nothing except every major brand, and every off brand, all lined up at the same place. This was up in the pan handle and all they refined was west texas intermediate. No ships, no foreign oil. Just plain old usa crude. Now I can't say if the tankers added stuff to their tanks or not but they all filled from the same place. After seeing that I don't care about brands. I buy at places with high volume so I can feel safe it's fresh is all I care about. I do stay away from the Hadji Marts since they get nailed for selling wrong octanes all the time.

 

Yes, it all comes from the same place, more or less, but you will get a bad batch now and then. I travel extensively in a Dodge PU and many tanks of fuel make it run like ****!

 

Like to go back to the good old days when we had Chevron white pump.!00 octane.Ran it in our race car.Very Very Good then

 

I noticed a little pinging when I fueled up at a local brand of stations. I called and complained to thier management that I didn't like buying Premium gas only to get regular instead. I see them pumping gas in all the tanks (regular,Plus,Premium) from the same trucks before. After my phone call The gas quality no longer makes my engine ping.

I suspect they are crooks looking to rip us off any way they can, or their truck drivers are dumber than rocks pumping Regular gas into Premium tanks at the stations. I think they know most new engines have knock sensors so they can put whatever they want in the tanks.

I truly despise anyone associated with the gas operators and like them to terrorists.

I know they are just crooks ripping us off and they don't intend to actually harm people, but corruption and theivery are on my hate list!

 

I use to deliver gas to our local stations and yes we all lined up the same place to fill our tankers. However, the controls inside the fill station are different for premium, regular, etc. so when we loaded we did get a different blend (octane).
Also we all sometimes put the wrong gas in the wrong tanks at the stations and usually the station just sold it as what it was suppose to be! Our punishment for making that mistake?--take a day off. Unfortunately we couldn't pick the day.

 

I use Shell 93 octane because it contains NO ethanol. It's one of the last few brands that doesn't put ethanol in their premium gas (at least here in WI). Car runs great on it!!

 

We have Chevron 94 octane here. It contains no ethanol and has its own dedicated nozzle. I run 91 most of the time, but recently noticed some pinging so ifilled with 94 and the car sounds happier.