Costco Premium Gas + Engine problems
Thread Starter
Junior Member
Joined: Jun 2014
Posts: 72
Likes: 2
2015 S550
Costco Premium Gas + Engine problems
For the last 3-4 months, I've had problems with my 2015 S550 with only 11,000 miles on it. On Park while in IDLE the engine sounds slightly rough & louder than normal and the car shudders slightly. When I accelerate on Gear 2 (rough throughout Gear 2 with my feet on the pedal) & the beginning on Gear 3 the engine sounds & FEELS strained and rough (almost truck like). I've taken the car to two different dealerships. The service advisors initially admit they can hear the the slightly rough engine sounds when I first show them the problem and take them on a ride in my car.
But inevitably the techs (including the shop foreman) claim that that there is no problem and it sounds normal to them after they run their diagnostics. My service Advisor now claims that its the exhaust/muffler that is making the noise due to the gas I use (Costco Premium gas) and that I should put some engine additives and switch gas brands. Does this sound right to anyone? Anyone else use Costco brand Premium gas?
But inevitably the techs (including the shop foreman) claim that that there is no problem and it sounds normal to them after they run their diagnostics. My service Advisor now claims that its the exhaust/muffler that is making the noise due to the gas I use (Costco Premium gas) and that I should put some engine additives and switch gas brands. Does this sound right to anyone? Anyone else use Costco brand Premium gas?
Super Member
Joined: Sep 2015
Posts: 725
Likes: 189
From: Chicago area
2015 E400 and 2015 GLK350
We've been using CostCo premium fuel in both the E400 and the GLK since new (almost 3 years now). Absolutely no problems. CostCo pledges to sell only top-tier gas that meets or exceeds all manufacturers' specs. Of course, it is always possible that your particular CostCo has water seeping into its underground tanks or other such problems. Can't hurt to try another name-brand, first without any additive, then if the problem goes away you know it is the gas. If the issue remains after a couple of tanks of name-brand gas, then I would try the additive (something like Techron - ask the Dealer which one they use in the service department). If name-brand gas with additive works, you can either stay with the name-brand but stop the additive, or go back to CostCo. You may have deposits or contamination in your fuel system, and the additive may help clean it out. If so, then you can drive for quite a while before it builds up again. At that time, just add another bottle of the magic additive and keep going.
I remember that with my W201, at each service the dealer service department always added a bottle of Techron to the fuel. I never had an issue, and that car ran perfectly for the 137K miles I drove it.
I remember that with my W201, at each service the dealer service department always added a bottle of Techron to the fuel. I never had an issue, and that car ran perfectly for the 137K miles I drove it.
Member
Joined: Dec 2017
Posts: 177
Likes: 23
From: Portland, OR
2018 S560; 2021 GLS450
I can also vouch for CostCo gas. I have been using it on all my vehicles since new, and never ever had any problems. Even with the infamous BMW F10 with N63 engine. I do use a bottle of Techron for the second from the last tank before any planned oil change though. And that one I can also vouch for.
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Joined: May 2002
Posts: 10,534
Likes: 3,669
From: Land of 10,000 lakes
AMG GTC Roadster, E63s Ed.1, M8 Comp. Coupe
Costco is a top tier fuel provider. They have to be certified for that.
Quality-wise rope tier are the best fuels so it’s nonsense
Quality-wise rope tier are the best fuels so it’s nonsense
Thread Starter
Junior Member
Joined: Jun 2014
Posts: 72
Likes: 2
2015 S550
I forgot to mention that i am getting about 13.7 mpg city/highway mixed. That seems low to me as well. what kind of MPG are you guys getting on your cars?
For the last 3-4 months, I've had problems with my 2015 S550 with only 11,000 miles on it. On Park while in IDLE the engine sounds slightly rough & louder than normal and the car shudders slightly. When I accelerate on Gear 2 (rough throughout Gear 2 with my feet on the pedal) & the beginning on Gear 3 the engine sounds & FEELS strained and rough (almost truck like). I've taken the car to two different dealerships. The service advisors initially admit they can hear the the slightly rough engine sounds when I first show them the problem and take them on a ride in my car.
But inevitably the techs (including the shop foreman) claim that that there is no problem and it sounds normal to them after they run their diagnostics. My service Advisor now claims that its the exhaust/muffler that is making the noise due to the gas I use (Costco Premium gas) and that I should put some engine additives and switch gas brands. Does this sound right to anyone? Anyone else use Costco brand Premium gas?
But inevitably the techs (including the shop foreman) claim that that there is no problem and it sounds normal to them after they run their diagnostics. My service Advisor now claims that its the exhaust/muffler that is making the noise due to the gas I use (Costco Premium gas) and that I should put some engine additives and switch gas brands. Does this sound right to anyone? Anyone else use Costco brand Premium gas?
Senior Member
Joined: Jan 2017
Posts: 485
Likes: 74
From: Marina Del Rey, CA
2015 MBZ S 550
‘I’ve driven my car 5,700 miles in the year and a half that I’ve owned it. It’s a mix of city and highway miles. I get 14.0 mpg.
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Senior Member
Joined: Apr 2016
Posts: 287
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From: Colorado
2004 W240 Maybach 57
If my math is correct, you are putting less then 3,000 miles per year on the car. (MY 2015 + 11,000 miles) Could you be making only short trips whereby the car is not getting up to full operating temp? If so, this could be allowing deposits in the engine (intake/exhaust valve train?) that would normally be eliminated by extended full temp running. Try some kind of fuel additive for cleaning valves and give the car some good runs.
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MBWorld Fanatic!
Joined: Mar 2017
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From: Birmingham, AL
2019 S560, 2022 Audi S8
If my math is correct, you are putting less then 3,000 miles per year on the car. (MY 2015 + 11,000 miles) Could you be making only short trips whereby the car is not getting up to full operating temp? If so, this could be allowing deposits in the engine (intake/exhaust valve train?) that would normally be eliminated by extended full temp running. Try some kind of fuel additive for cleaning valves and give the car some good runs.
MBWorld Fanatic!
Joined: Oct 2002
Posts: 4,975
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From: Cincinnati
2010 E350 4Matic
For the last 3-4 months, I've had problems with my 2015 S550 with only 11,000 miles on it. On Park while in IDLE the engine sounds slightly rough & louder than normal and the car shudders slightly. When I accelerate on Gear 2 (rough throughout Gear 2 with my feet on the pedal) & the beginning on Gear 3 the engine sounds & FEELS strained and rough (almost truck like). I've taken the car to two different dealerships. The service advisors initially admit they can hear the the slightly rough engine sounds when I first show them the problem and take them on a ride in my car.
But inevitably the techs (including the shop foreman) claim that that there is no problem and it sounds normal to them after they run their diagnostics. My service Advisor now claims that its the exhaust/muffler that is making the noise due to the gas I use (Costco Premium gas) and that I should put some engine additives and switch gas brands. Does this sound right to anyone? Anyone else use Costco brand Premium gas?
But inevitably the techs (including the shop foreman) claim that that there is no problem and it sounds normal to them after they run their diagnostics. My service Advisor now claims that its the exhaust/muffler that is making the noise due to the gas I use (Costco Premium gas) and that I should put some engine additives and switch gas brands. Does this sound right to anyone? Anyone else use Costco brand Premium gas?
Last edited by MBNUT1; Jun 22, 2018 at 08:11 PM.
Member
Joined: Dec 2010
Posts: 115
Likes: 21
From: Calgary
2014 S550 4matic, 2014 Corvette, 2016 Camaro SS 2011 Lexus RX350
My 2014 had a couple of fuel injectors go at about 5000 mi. Some manufacturing issues I don't know for how long, maybe a TSB on your car. There is a TSB thread.
Usually/maybe a check light results
Usually/maybe a check light results
