Costco 91 octane

[mit_peid]

What are people's opinion's on Costco 91 octane gas? I know generally California gas sucks, but does Costco gas suck worse than say Shell, Chevron, Mobil, etc? I have a buddy that works at a refinery and he basically said all gas is pretty much the same because they come from the same few refineries (as long as it is the same octane).

I like Costco since it is cheaper than most (especially with the AMEX rewards) and it is close to my house, but I seem to get slightly worse gas mileage (and performance?) with Costco. Not quite sure if it is the gas itself or variances in my driving style and city/hwy split.

[trekkie]

It's fine. You see hundreds of car forums where people are asking, and lots of people posting no issues.

They have to have a detergent by law, so there's no concern there anymore.

[Mo707]

i feel like costco gas burns too quick. I went threw a full tank of costco gas in a day. I only use chevron 91 octane now. lasts way longer IMO.

[R.S-HawK]

93 Shell V Power is the way to go, not sure if they have it in Cali.

[Urmyson]

I used to work for a Fuel Transportation Company. Most of the Gas stations get their gas from the same fuel rack for that area. There are two fuel racks in my area and it has to come from one of them. BJ's, Hess, BP, and many other stations all get the same gas, at least when they ordered from us. Your area could be different, but after working there i just look for the cheapest price now because they all come from the same source.

[zooki]

Gasoline does only come from a few refineries. The additives are different however. I have a tank farm near my house, and I see trucks from all of the major brands pull in there. I'm told the drivers have an additive package they add to the trailer before they fill up. I always try to buy from a gas station that does a lot of business so it turns over the inventory quickly.

[nelsmar]

Doesn't last as long, works better... so many strange ass responses you see in threads like this. How about some real info?

I hosted a dyno event in Arizona. I organized getting a number of individuals cars e-tuned prior to the event to "prep" and shorten their time on the dyno. Arizona pumps like other areas come from very few locations. Basically all of the pumps in Phoenix come from one of very few places and are the same from pump to pump. The difference is additives, and how long it sits.

During our testing the tuner we worked with kept complaining about random users cars and we started investigation who was pumping where. We found that oddly enough the users with costco fuel were having the least issues. Our assumption was that the fuel was sitting less and was always "fresh" due to the more volume costco was pushing through their pumps. Knock feedback was more constant on costco than some of the other pumps in the area. We didn't exactly test shell vs chevron etc. But had just noticed that after telling someone to go to costco and fill up, or to a previously used pump we saw consistently bad/good results.

So unless you have data logs (like i do), dynos (like I do), or have looked into your engine physically before switching brands... your post is likely just your opinion and a placebo effect guys. Clear the ecu, run 2-3 tanks of one brand, clear the ecu, run 2-3 tanks of the next brand and then compare the logs to see how the knock feedback is if you are looking for performance differences.

[infinite012]

Originally Posted by Mo707

i feel like costco gas burns too quick. I went threw a full tank of costco gas in a day. I only use chevron 91 octane now. lasts way longer IMO.

This just quantifies that you're an idiot.

[Mikem53]

Originally Posted by Mo707

i feel like costco gas burns too quick. I went threw a full tank of costco gas in a day. I only use chevron 91 octane now. lasts way longer IMO.

That makes no sense.. I use costco, shell, Exxon with the same results..
Basically.. Only the additive packages are different.. It's all in your head..

[ja1217]

I run Costco 93 (east coast) all the time. Cars been running fine and actually made 181 whp with the only power mod being a K&N filter and stock tune.

[eikond]

This is an interesting question.. one that I've been thinking a little about.

I've read that the detergents put in the cheaper gas aren't as good.. as a result they can leave a little more deposit on the valves, etc.. over time those deposits can build up and cause some detonation issues. This is normally not an issue with standard (non-direct injection), but I've heard that on DI motors this is a little more of a problem..

I know a co-worker has a Chevy SUV that states this explicitely in the owner's manual.

Anyone have input on this?

[zooki]

I found this article:
http://www.nytimes.com/2002/11/22/tr...ted=all&src=pm
While it was written a while back I don't think too much has changed. It's interesting what people who are in the industry and do actual testing have to say about the different brands.

[calmtigers]

Just to rehash what everyones been saying.

All of the gas in your area is probably from the same/close to the same refinery.
Due to Calif Law detergents must be added, all gasoline has about 10% Ethanol, and actually has had it for a long time now (not just recently)
Additives are kind of a pointless "fancy ribbon" thing between oil companies..

Source: parents own multiple gas stations, more so I log in gas invoices and they show the breakdown of whats in it now

[eikond]

Originally Posted by calmtigers

Just to rehash what everyones been saying.

All of the gas in your area is probably from the same/close to the same refinery.
Due to Calif Law detergents must be added, all gasoline has about 10% Ethanol, and actually has had it for a long time now (not just recently)
Additives are kind of a pointless "fancy ribbon" thing between oil companies..

Source: parents own multiple gas stations, more so I log in gas invoices and they show the breakdown of whats in it now

Good info!

One follow-up question.. These additives that the gas companies advertise.. when/where are they added? Do they go in at the refinery? Or at the holding tanks/distribution facility? Or are they added by the truck that delivers? Or even dumped into the tanks at the station itself?

Just curious..

Thanks

edit* I read the link in the post above.. sounds like the company specific additives are added into the trucks as they fill at the distribution facily. For example: "one measured squirt every 40 gallons".