Costco versus Chevron/Shell or any Top Tier gas?
Super Member
Joined: May 2010
Posts: 684
Likes: 1
From: Leesburg, VA
2014 E550 4Matic with P1/LED/Pano
same....Costco only for nearly a decade (and see the list of modified/tuned cars we've had.....tuned for 93oct). I recently had to get Citgo on a road trip and my idle was ROUGH. SO HAPPY to fill up at Costco again last Friday.....car is back to normal.
The other thing to keep in mind; Costco sells SO much gas, they get daily deliveries. That means the gas isn't sitting in a tank for a week at a time, letting any residual sediment collect at the bottom. The old rule about NOT refueling at a station that's getting a delivery is a good one (sloshing in the tank and mixing up anything at the bottom); but at Costco, its not relevant.
The other thing to keep in mind; Costco sells SO much gas, they get daily deliveries. That means the gas isn't sitting in a tank for a week at a time, letting any residual sediment collect at the bottom. The old rule about NOT refueling at a station that's getting a delivery is a good one (sloshing in the tank and mixing up anything at the bottom); but at Costco, its not relevant.
Joined: Jul 2006
Posts: 6,760
Likes: 594
From: Seattle
'19 E63S, ‘16 CLS63 RIP, '09 E63 Gone, '06 M5 Gone, '97 Supra TT Gone
This is only partially true. Gas is also treated with additives and detergents that differ from company to company. Chevron has "Techron" for instance which is a great injector cleaner. The additives help your car run healthier and cleaner. For me, I try to get to Shell whenever I can.
Member
Joined: Sep 2011
Posts: 112
Likes: 0
Acura TL-S 2002
Costco or SAMs do not have these gas additives, so in the long run it is not good for the engine. If you plan to keep your car for many years, you may lose more than you gain on the gas price difference.
Costco and such also do not have the highest octane number gas. If your engine has a high compression ratio and requires premium gas, you may hear "knocking" that is not good for the engine, because the gas ignites due to pressure and pushes the piston down while it is still going up. This reduces the power, gas mileage, and engine longevity.
Test your gas mileage. If it is the same with Costco gas, you should be fine. Otherwise chances are you are losing more than saving and not only on gas.
If your car requires premium gas, the rule of thumb is to go with the highest octane rating. Here in Kansas City it is BP with 93 vs. 91 at Costco.
Costco and such also do not have the highest octane number gas. If your engine has a high compression ratio and requires premium gas, you may hear "knocking" that is not good for the engine, because the gas ignites due to pressure and pushes the piston down while it is still going up. This reduces the power, gas mileage, and engine longevity.
Test your gas mileage. If it is the same with Costco gas, you should be fine. Otherwise chances are you are losing more than saving and not only on gas.
If your car requires premium gas, the rule of thumb is to go with the highest octane rating. Here in Kansas City it is BP with 93 vs. 91 at Costco.
Trending Topics
MB World Stories
The Best of Mercedes & AMG
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
5 Underrated Mercedes-Benz Models That Don't Get the Love They Deserve
Verdad Gallardo
Mercedes 300D Has Pushed Well Past 1 Million Miles and It Ain't Stopping
Verdad Gallardo
10 Most Reliable Mercedes-Benz Models You Can Buy Used
Verdad Gallardo
Super Member
Joined: Dec 2004
Posts: 783
Likes: 22
From: Atlanta
06 E55 Black
Costco or SAMs do not have these gas additives, so in the long run it is not good for the engine. If you plan to keep your car for many years, you may lose more than you gain on the gas price difference.
Costco and such also do not have the highest octane number gas. If your engine has a high compression ratio and requires premium gas, you may hear "knocking" that is not good for the engine, because the gas ignites due to pressure and pushes the piston down while it is still going up. This reduces the power, gas mileage, and engine longevity.
Test your gas mileage. If it is the same with Costco gas, you should be fine. Otherwise chances are you are losing more than saving and not only on gas.
If your car requires premium gas, the rule of thumb is to go with the highest octane rating. Here in Kansas City it is BP with 93 vs. 91 at Costco.
Costco and such also do not have the highest octane number gas. If your engine has a high compression ratio and requires premium gas, you may hear "knocking" that is not good for the engine, because the gas ignites due to pressure and pushes the piston down while it is still going up. This reduces the power, gas mileage, and engine longevity.
Test your gas mileage. If it is the same with Costco gas, you should be fine. Otherwise chances are you are losing more than saving and not only on gas.
If your car requires premium gas, the rule of thumb is to go with the highest octane rating. Here in Kansas City it is BP with 93 vs. 91 at Costco.
Sweeping generalizations. Here in Atlanta 93 is available at Costco and what evidence can you provide that absence of unspecified additives "is not good for the engine"
Joined: Jul 2006
Posts: 6,760
Likes: 594
From: Seattle
'19 E63S, ‘16 CLS63 RIP, '09 E63 Gone, '06 M5 Gone, '97 Supra TT Gone
http://en.wikipedia.org/wiki/Top_Tie...rgent_Gasoline
In fact I'm going to dump a bottle of techron in my car next time I gas her up.
Last edited by Cylinder Head; Sep 21, 2011 at 11:46 AM.
Super Member
Joined: May 2010
Posts: 684
Likes: 1
From: Leesburg, VA
2014 E550 4Matic with P1/LED/Pano
I just got 26mpg on my car on a road trip from VA to NC. More than good for a big V8 and auto transmission, loaded with three people and junk.
MBWorld Fanatic!
Joined: Dec 2008
Posts: 2,396
Likes: 38
From: Bay Area, CA
2007 SL55 AMG
I've used costco many times before and have not noticed any worse gas mileage. I tend to alternate between costco and chevron though, whichever one is more convienient for me when my tank gets empty.
MBWorld Fanatic!
Joined: Oct 2009
Posts: 2,825
Likes: 17
From: Southern California
E55 w/ goods, Z32 Project underway
I waste more time than it is worth waiting in line at one of those warehouse stations. Lines are out to the street for what? To save pennies which will never add up enough to justify the wasted time. At least for me. Any of the large premium chains for me with no wait. I will pay the extra .20 a gallon to get in and out.
Last edited by pearlpower; Sep 21, 2011 at 01:12 PM.
MBWorld Fanatic!
Joined: Mar 2008
Posts: 1,230
Likes: 32
From: Vancouver, BC
CLS55 AMG
chevron 94 octane only for me... yes in Canada we get 94 octane :P. Shell gas is the worst out of them all up here, it's been known to kill people's fuel pumps. I even noticed worse performance when I filled up at Shell once... so I stick to Chevron
MBWorld Fanatic!
Joined: Sep 2005
Posts: 1,558
Likes: 8
From: Sacramento, CA
Ducati
I waste more time than it is worth waiting in line at one of those warehouse stations. Lines are out to the street for what? To save pennies which will never add up enough to justify the wasted time. At least for me. Any of the large premium chains for me with no wait. I will pay the extra .20 a gallon to get in and out.
Not to mention the Costo/Sams fueling stations are pretty far off the beaten path, with many speedbumps between.
I will happily pay an extra .10-.20 to not have to deal with lines, going out of the way, and speedbumps. Mainly speedbumps.
Super Member
Joined: Sep 2010
Posts: 798
Likes: 4
From: HTX-->ATL -->CHI
2015 E63S 4Matic
It's all the same. I grew up in the oil industry and my father is a former exec at COP and current Global Manager of Hydrocarbons at a separate company so this came up at dinner a lot growing up 
Personally, I've been using Costco [93] forever, but if I'm not near a costco I go to whatever is closest.
But valero, exxon, shell, texaco, or a murphy oil distributor all sell you the same stuff.
As for your detergent argument, whoever mentioned it... it's been government mandate since 1994 to add detergents to ALL gasoline.
Personally, I've been using Costco [93] forever, but if I'm not near a costco I go to whatever is closest.
But valero, exxon, shell, texaco, or a murphy oil distributor all sell you the same stuff.
As for your detergent argument, whoever mentioned it... it's been government mandate since 1994 to add detergents to ALL gasoline.
MBWorld Fanatic!
Joined: Jan 2004
Posts: 7,092
Likes: 13
From: Salt Lake City (but not Morm)
2003 E55 & 2014 GL550
Local station literally opened 12 months ago and we watched them install those massive tanks. Brand new tanks = no junk in the gas (or not much).
It's all locally made around here anyway at the local refinery so it's mostly the same stuff.
Due to elevation, no 93 here. Tuners claim I am overkilling it even with 91 with my DA (6500ft in summers) but I will just take my chances.
It's all locally made around here anyway at the local refinery so it's mostly the same stuff.
Due to elevation, no 93 here. Tuners claim I am overkilling it even with 91 with my DA (6500ft in summers) but I will just take my chances.
Super Member
Joined: Oct 2009
Posts: 923
Likes: 0
From: Jacksonville, Florida
2006 E55 AMG --old cars -- E39 M5, 2.7tt Audi S4, E36 M3 **Ducati 996, 748
sams and costco no problems --- only had a idle problem twice after using 76 -- So, I dont use that station's gas anymore.
