Costco TT Premium

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Since there are a lot of discussions on fuel quality and additives, I thought I would report my experience. Last year I bought a 19 yr. old(now 20) MB CLK 430 with the 4.3 v8 with 98k miles on it. It seemed to run a little rough so I filled it with Costco Prem. After 3or 4 tanks, I noticed it was running smoother and quieter. I used no fuel additives. The car had questionable maintenance so I changed all fluids. As a side note, one of the lifters was ticking loudly until the engine was hot. I put in 1.5 cans of LiquiMoly Hydralic lifter conditioner. It took several hundred miles but it has quieted down to normal.
I didn't realize how rough it was until it was cleaned out.
 
Nothing like buying a high mileage german vehicle with questionable history. Hope it works out for you
 
Originally Posted by ad244
Nothing like buying a high mileage german vehicle with questionable history. Hope it works out for you

"Like"
 
I'll vouch for Costco gas.

Ever since suspecting that my 2011 Hyundai Accent's computer was lying to me about my MPG (turned out I was right), I've been hand calculating MPG with every fillup since 2011. It got to be a habit.

My weekly driving is extremely consistent with regards to miles driven, route, traffic, tire pressure and weather conditions. The only thing that changes is driving with the A/C on in summer and off in winter.

Using Costco gas (regular) to fill up my Crown Vic for the last five years, I ALWAYS get 4-5% better MPG than other TT.

Also, compared to Valvoline and PUP in 10,000 mile OCIs, the Kendall oil in my signature gives me 4-5% better fuel economy.

Together, Costco gas and Kendall oil consistently give me 9-10% better fuel economy. I'm not big on brand loyalty but based on my experience I stick to these two brands.
 
You'll notice that MB requires premium gas, as in the owner's manual if you have one.
MB has always refused to say that 87octane is OK on daily use they specifically mention premium, I was also surprised that it was so in a V8.
IMO though one pays a bit more for the gas the benefits over time far outweigh the cost.
 
Originally Posted by shiny


Using Costco gas (regular) to fill up my Crown Vic for the last five years, I ALWAYS get 4-5% better MPG than other TT.

Also, compared to Valvoline and PUP in 10,000 mile OCIs, the Kendall oil in my signature gives me 4-5% better fuel economy.

Together, Costco gas and Kendall oil consistently give me 9-10% better fuel economy.

If the Costco gas has no ethanol vs other gas with 10% ethanol, you might see 2 - 3% better.
As for oil brand specific mpg improvement, unless you're running SAE testing procedures, call me unconvinced.
 
Costco claims to put extra injection cleaner into both regular and premium fuel, just like the other TT vendors. In any case, where we live it is at least 20c /gal cheaper, and often around .50c . Of course, we end up buying more at Costco which is the point of the cheaper gas. I mostly like their extremely fast gas pumps.
 
Originally Posted by Kestas
I read the title and thought this was a thread on TurboTax Premium.


And I thought I was weird. I thought it Toilet Tissue Premium. They do got some great toilet paper.
 
Originally Posted by ad244
Nothing like buying a high mileage german vehicle with questionable history. Hope it works out for you

Just what are you insinuating? I bought it for a great price, put front brakes on it, recharged the ac, and changed all drivetrain fluids and it runs great and everything works like it should. No cracks in leather. It was a garage queen in Mn. and Wisc. It's my Florida car for the winter. Maybe 1k miles a yr. I leave it here.
 
Originally Posted by Pelican
You'll notice that MB requires premium gas, as in the owner's manual if you have one.
MB has always refused to say that 87octane is OK on daily use they specifically mention premium, I was also surprised that it was so in a V8.
IMO though one pays a bit more for the gas the benefits over time far outweigh the cost.

I knew they need premium. I was just commenting on the clean up job the Costco Prem did. My daughter has a 99 ML with the 3.2 v6. She is the second owner. It always had premium and synthetic oil every 5-7k miles, not 10k like MB says. She now has over 220k on it and it runs so nice it worries me.LOL It uses maybe half a qt between changes.
 
Has anyone with GDI had problems with Costco gas? I have a 2018 Subaru Legacy non GDI and a 2019 Subaru Impreza which is GDI. The Legacy gets ~ the same MPG with Costco or BP but I have been having issues with the Impreza and the dealer told me that it is due to Costco gas and they had a few cars in recently where they had to empty the tank due to Costco gas. I "should" be getting ~27 city and ~36 highway. I'm getting between 18-20 city. They asked me to try a different brand for a few tanks and it "will" get better. They also said the jerkiness of the CVT is due to the gas.

Any thoughts? Anybody have this problem?
 
Originally Posted by Wheel366
Has anyone with GDI had problems with Costco gas? I have a 2018 Subaru Legacy non GDI and a 2019 Subaru Impreza which is GDI. The Legacy gets ~ the same MPG with Costco or BP but I have been having issues with the Impreza and the dealer told me that it is due to Costco gas and they had a few cars in recently where they had to empty the tank due to Costco gas. I "should" be getting ~27 city and ~36 highway. I'm getting between 18-20 city. They asked me to try a different brand for a few tanks and it "will" get better. They also said the jerkiness of the CVT is due to the gas.

Any thoughts? Anybody have this problem?


Costco is Top Tier (US, Canada, Mexico) Top Tier Brands

Two DI engines in our stable and we have been using Costco gas almost exclusively for about 4 years with no issues.
 
Last edited:
Originally Posted by BMWTurboDzl
Originally Posted by Wheel366
Has anyone with GDI had problems with Costco gas? I have a 2018 Subaru Legacy non GDI and a 2019 Subaru Impreza which is GDI. The Legacy gets ~ the same MPG with Costco or BP but I have been having issues with the Impreza and the dealer told me that it is due to Costco gas and they had a few cars in recently where they had to empty the tank due to Costco gas. I "should" be getting ~27 city and ~36 highway. I'm getting between 18-20 city. They asked me to try a different brand for a few tanks and it "will" get better. They also said the jerkiness of the CVT is due to the gas.

Any thoughts? Anybody have this problem?


Costco is Top Tier (US, Canada, Mexico) Top Tier Brands

Two DI engines in our stable and we have been using Costco gas almost exclusively for about 4 years with no issues.


I actually told them that Costco is Top Tier and the told me that for some reason these cars don't run well using Costco gas. I have to do my due diligence and use a different brand for a few tanks and go from there. I also think they have no idea how to even tackle the problem.
 
My son has the 2020 Impreza and is already getting 36 MPG with only 2,500 miles on the car so far, and he just buys from whatever gas station he comes across. He had no brand preference whatsoever.

There are no Costco gas stations near us so you Subaru dealer may be right, that Costco gas is causing your issues.
 
been using Costco Top Tier goalies for nearly 6 years now...in a variety of vehicles, several GDIs...not issues that are the fault of the gasoline...

there are many here and elsewhere that equate inexpensive with cheap...Costco is Top Tier and meets or exceeds any requirement for Top Tier and should not give your engine any issues...A/C Delco filters sold at Walmart are the same as A/C Delco filters sold elsewhere, Motorcraft same...Mobil 1 at Walmart is the same Mobil 1 sold at any more expensive store...

Good luck with your choice

Bill
 
If the local Subaru dealer is experiencing drivability problems with Costco gasoline in that particular FB20 DI engine used in the new Impreza, that seems like a pretty good reason to switch brands of gasoline for 5-6 tanks as the dealer recommends and watch the problem clear up. Why wouldn't you? It would seem foolish not to.

Most people do not just start talking about a brand of gas at their car dealership so if the question gets asked and bingo, the guy uses Costco brand gas, there just might be something to it.

In any case there is no reason to White knight for Costco gasoline.
 
While I am of the mindset that Costco gas is not the issue, the solution is easy and a no brainier. Try another brand for 10 tanks and compare.
 
Both my wife and I use Costco TT gas and have no issues. Sometimes I will fill up at Shell across the street if the Costco station is closed, however we don't see any drop off on MPG or performance.




2010 Honda Civic EX
2008 Acura TL Base
 
Last edited:
Originally Posted by loneryder
Since there are a lot of discussions on fuel quality and additives, I thought I would report my experience. Last year I bought a 19 yr. old(now 20) MB CLK 430 with the 4.3 v8 with 98k miles on it. It seemed to run a little rough so I filled it with Costco Prem. After 3or 4 tanks, I noticed it was running smoother and quieter. I used no fuel additives. The car had questionable maintenance so I changed all fluids. As a side note, one of the lifters was ticking loudly until the engine was hot. I put in 1.5 cans of LiquiMoly Hydralic lifter conditioner. It took several hundred miles but it has quieted down to normal.
I didn't realize how rough it was until it was cleaned out.

Buy Mobil, Exxon, BP, Marathon or Sunoco for several fill-ups and see if the problem goes away. Since Costco gas is affiliated with Shell gas, don't buy Shell until the issue is resolved.
 
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