2014 Buick Verano T, 5067 miles, M1 5w30 HM

[A_Harman]

Fuel dilution is still a major issue. I shortened the change interval to ~5000 miles, but the oil still fell out of grade.
Running the injector cleaner early in the oil change interval apparently didn't help the fuel dilution.
And starting to run E85 fuel mixtures in the last part probably didn't help either.
Iron wear metal is down a decent amount, probably due to the reduced OCI. Wear rate is lower on the new report in terms of PPM/kilomile. Small comfort.

Maybe it needs new injectors, or a new DI pump.
I could live with the problem by going to a thicker oil and figuring out an OCI to keep the oil in grade.
But it's probably better to find and fix the problem.

 

[JavierH19]

I think i mentioned in a previous post to just use a whatever syn blend 10w-40 and change at 5k intervals. It doesn't really need new anything it's just how these early turbo gdi ecotecs are by nature. I wouldn't worry about it too much. Just bump up a grade and change at 5k or under and live life.

 

[MParr]

Try a 5W40 Euro oil.

 

[A_Harman]

Wanting to estimate how much fuel is required to dilute the oil to the amount shown in the UOA, I went to the Widman viscosity calculator and used the percentage of two oils function:

To get the 8.5 cSt reading from the current UOA:

11.9 is the kinematic viscosity of M1 5w30 HM at 100C, and .55 is the kinematic viscosity of gasoline.
(I found a webpage that has 3 values for gasoline @ 100C. They were .71, .55, and .40. I used the middle value.)
It takes about 10% fuel dilution of the oil to get 8.5 cSt.

To get the 8.1 cSt reading from the first UOA:

The original UOA was for Mobil 1, so the oil viscosity is less.
Interesting that the dilution amount is still 10%. I wonder if that means the dilution amount increases quickly to 10% and then stays there because the oil gets hot enough to boil off fuel amounts above that, or if the fuel dilution rate is increasing and only took 5000 instead of 7600 miles to get there.

If I want to go up a grade, what viscosity oil would be necessary to keep from dropping out of the 30 grade with 10% dilution:

13.1 cSt is a light 40, so it isn't necessary to go very thick.
I think I need to dump the current fill before 5000 miles and try a 40-weight.

 

[addyguy]

5W-40 or 0W-40 Euro oil would be a good next step here.
Even given the thinning, wear is not bad, as you have noted,

 

[OVERKILL]

Good Lord that's a lot of fuel! What's the driving pattern like?

 

[A_Harman]

Good Lord that's a lot of fuel! What's the driving pattern like?

136 miles daily round-trip for work, so it's not short-tripping.

 

[OVERKILL]

136 miles daily round-trip for work, so it's not short-tripping.

Sweet Jesus!!!! Are there any ECM updates or anything for this? That's just not right!

 

[A_Harman]

Sweet Jesus!!!! Are there any ECM updates or anything for this? That's just not right!

I've been searching Buick TSB databases, and haven't found any that are about fuel dilution.

 

[OVERKILL]

I've been searching Buick TSB databases, and haven't found any that are about fuel dilution.

I wonder if @Trav knows of any issues on maybe leaking injectors or something?