Increased fuel dilution with Shell Gas (1.5T Civic)

[parshisa]

So, I usually fill up with Costco Premium (pretty much 100% of the time for my 1.5T Civic) but this time around I was running very low on gas and filled up with Shell 93. With really no change to weather as well as my driving patterns my mileage dropped by 2mpg as well I noticed oil level increase on the dipstick. Did a droplet test and sure enough gas ring was enormous confirming my suspicion (usually, when I run this test gasoline ring is minimal. less than 1mm). Next fill was costco and within one tank level pretty much dropped back to where it was as well as mileage has improved.

I'm a little confused as to why this would be happening given both fuels are the same octane rating and supposedly should perform the same way. Any ideas?

 

[badtlc]

It is an engine problem, not a fuel problem.

 

[parshisa]

I'm not saying fuel dilution is uncommon for these engines. What I'm saying is my experience with not seeing any side effects of this phenomenon with one fuel and observing them with another one. While I do appreciate your time responding to my inquiry I have to admit that it doesn't bring too much value to the table.

 

[Cujet]

Interesting. The first guess would be the fuel is different.

 

[parshisa]

They probably are as far as cleaning agents package goes. But should be the same octane rating therefore no change in engine timing should occur, correct?

A little history: I've been running regular gas for the first 8K on the car and was seeing increase in levels but once switched to premium ran costco exclusively and never had any issues (major issues) with fuel dilution.

 

[slo town]

Maybe you got a bad tank of fuel from the Shell station....? And for all you know, Costco buys its gasoline from Shell.

Regardless, this one instance does not prove anything. Experiment again using other gasoline brands.

Scott

 

[parshisa]

Could be the case. And I'm really not making any statements with my post, instead looking for member's opinion and possibly similar experience.

As much as I like experiments I usually prefer to stick with what works.

 

[Pelican]

Originally Posted by parshisa
So, I usually fill up with Costco Premium (pretty much 100% of the time for my 1.5T Civic) but this time around I was running very low on gas and filled up with Shell 93. With really no change to weather as well as my driving patterns my mileage dropped by 2mpg as well I noticed oil level increase on the dipstick. Did a droplet test and sure enough gas ring was enormous confirming my suspicion (usually, when I run this test gasoline ring is minimal. less than 1mm). Next fill was costco and within one tank level pretty much dropped back to where it was as well as mileage has improved.
I'm a little confused as to why this would be happening given both fuels are the same octane rating and supposedly should perform the same way. Any ideas?


It would be a fuel problem only if you got a bad batch, otherwise it doesn't make sense. The increase in the oil would be due to unburnt fuel and not likely if the fuel was fresh.

 

[anndel]

Anything is possible. It could be the gas itself or the detergents/additives. I could be the engine reacting to the Shell gas. Maybe a better analysis would be a UOA on both Costco and Shell gas (one UOA for each brand of gas) and using the same brand/type of oil and filter.

 

[Bjornviken]

Water in fuel? Happen to me last week. But i did have starting problems.

 

[parshisa]

No sir, car ran fine with exception of lower mpg achieved so I don't think water was the culprit

 

[Bjornviken]

Originally Posted by parshisa
No sir, car ran fine with exception of lower mpg achieved so I don't think water was the culprit


Ok, Wrong fuel type by mistake, thats happen sometimes.

 

[ka9mnx]

Different Winter mix?

 

[parshisa]

negative as well. I am 100% sure it was 93 octane (premiuim)

 

[parshisa]

I'm not sure if they use winter mix in gulf coast texas?

 

[JohnnyJohnson]

Originally Posted by Cujet
Interesting. The first guess would be the fuel is different.



Yes trust me not all gas that comes out of the Pipeline even from the same refiner is of equal quality.

 

[parshisa]

That makes sense although paying premium for "premium" I would expect equal quality across the board. Not always the case, obviously, I understand...

 

[PimTac]

Originally Posted by parshisa
I'm not sure if they use winter mix in gulf coast texas?




That would have to be verified by the maker. I can't imagine they would keep the summer blend for one region though I've been surprised before.

 

[MParr]

It could have been a higher percentage of Ethanol in that Shell gas and or the tanker operator dropped the wrong grade of fuel in the wrong tank.

 

[GMBoy]

I wonder if it could just be the Shell gas and it's better additive package is cleaning deposits that the Costco gas has been leaving behind all this time?