UOI GC 8.0K 2YEARS cSt 100C = 14.2 ?

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JimPghPA

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This is the first UOI for our 2001 Impala with the 3.4 L engine and 75,067 miles at the time of oil sample.

Oil analysis kit was NAPA "FIL 4077" for $14.35 + tax.

We purchased this vehicle with 30K miles on it 9 years ago, and ran Mobil drive clean 5000 5W30 with 3K OCI, until 13K miles ago.

Then I switched to GC, both to help stop some minor oil leaks and to go with longer oil changes.

Ran GC with new Purolator extra long oil filter PL24011 for 5K on the first fill of GC.

Then I ran this most recent fill of GC with new PL24011 for 8K miles over 24 months.

The oil analysis from NAPA calles TBN "Physical/Chemical Base Number (mgKOH/g)" and the report shows a value of 2.0

I know anything lower than 1 is no good, so I guess a value of 2 (even though I did not know this value at the time) was a good time to change it. I figured 2 years was about the maximum I wanted to run GC for, and with 8K on it that was certainly better than the 3K OCI I use to run, as far as getting my moneys worth out of an oil change.

Everything about the oil report is OK except that the viscosity came back as "Viscosity (cSt 100C) 14.2 Abnormal"

There was no make up oil for the 2 year 8K run of GC. The original viscosity of GC is supposed to be 12.1 (just below the maximum of 12.2 for a 30 weight).

Has anyone else seen GC having an increase in the viscosity with any similar amount of use?

I know 14.2 is about the middle of the 40 weight range, and certainly the engine was harmed running an oil that thick. But it is puzzling how an oil like GC can end up with a thicker viscosity than it probably had when new. I have read about oils shearing and having a reduction in viscosity. But I have no idea how an oil, especially an oil like GC, ends up with a thicker viscosity?

Any ideas of what could be going on causing the viscosity to show up as 14.2 after 2 years and 8K miles?

Here it the full report:

------------------------------------------------------------------------

Oil GC0W-30 Castrol European Formula
Miles in use 8,025
Miles on vehicle 75,067

Lab no. 41020697237 (the Ohio lab for for NAPA UOI)

Metals (ppm)

Iron (Fe) 110
Chromium (Cr) Lead (Pb) 196
Copper (Cu) 45
Tin (Sn) 7
Aluminum (Al) 21
Nickel (Ni) Silver (Ag) Titanium (Ti) Vanadium (V)
Contaminants (ppm)

Silicon (Si) 23
Sodium (Na) 67
Potassium (K) 5
Water (%) Coolant No

Additives (ppm)

Magnesium (Mg) 445
Calcium (Ca) 1626
Barium (Ba) Phosphorus (P) 781
Zinc (Z) 965
Molybdenum (Mo) 12
Boron (B)
Physical Tests

Viscosity (cSt 100C) 14.2 Abnormal

Physical/Chemical

Base Number (mgKOH/g) 2.0

-----------------------------------------------------------------------------------

Please feel free to make any comments regarding this report.

The 14.2 Aby-Normal viscosity for GC is puzzling to say the least.

At least it did not thin out.

Thanks in advance for any ideas of what is going on here.

Sincerely,



JimPghPa

PS: to the moderators, I wrote this report taking time to have all the numbers aligned in one column like shown in the post about how a report should look. But when I hit Preview Post something somewhere in the combination of all the software, deleted the extra spaces that made all this line up. I then tried using the tab key to get things to align, and still an no go on getting the numbers into columns. Sorry, but I did try.
 
Holy wear metals! I'm baffled as to why they are so high unless the GC is walking out residue that contains all those metals.
People run a grade thicker in engines all the time so I don't see why slightly thicker oil would cause additional wear HOWEVER wear metal like that could mean its too thick at start up and your getting alot of metal on metal wear.
Thank you for posting.
 
Ran it too long. Oil broke down. Oil first thins then it thickens as did your oil. Shorten the oci.
 
Oxidative thickening. If this lab gave oxidation and TAN numbers, we may find out it's corrosive wear.
 
Last edited:
Originally Posted By: FZ1
Ran it too long. Oil broke down. Oil first thins then it thickens as did your oil. Shorten the oci.

Really?
So that's always the case then?
I disagree. With a tbn of 2 the oil still has active additive left,so the oil hasn't broken down. Wear teals like that point to a mechanical issue. I doubt very much that at 8000 miles the oil has broken down.
I see it often that grades with less viscosity index improvers tend to thicken with use,unless fuel diluted.
 
It's done when it thickens. Further,the op needs to get all that wear metal out of the sump by changing the oil more frequently.
 
WOW, sorry for a BIG type error here, it should have read NOT harmed. Typing at the end of the day sometimes ends up with the mind wondering and missing a big type error. Sorry, but it was an honest mistake on my part.

I am certain the engine was not harmed from running an oil with that viscosity.

The real question is how did GC end up with a 14.2 viscosity.
 
Originally Posted By: FZ1
It's done when it thickens. Further,the op needs to get all that wear metal out of the sump by changing the oil more frequently.


GC has traditionaly oxidized in UOA's in some applications. I would hardly say that the oil was done. But is the 14.2 a typo? That is well out of grade.
 
Originally Posted By: JimPghPA
BTW, where would an oil pick up Lead. I do not know of where in an engine Lead would be use?


Some oem's still use bearings that contain lead. I would assume that's where it's coming from.
Honestly op. run a short 5000 mile run and test the oil again. See if this is a mechanical issue or just a one off bad run. Maybe a few short runs of a conventional and go from there.
With wear metals like that I'd use a cheaper oil and change more often. In reality a conventional should be able to handle 8000 miles,so you aren't seeing much of a cost savings,especially if your engine is dissolving.
 
The 14.2 is not a type error.

As for fuel treatments. I use Sta-Bil red for 55 gallons of winter fuel stored for the generators in 22 X 2.5 plastic jugs (55 Gallons). And again Sta-Bil red for 20 gallons of summer gas for the generators. That gas gets used up in both cars. I have used Sea-foam gas treatment, but I can't remember if the last time I used it was before the beginning of that last run of GC in the Impala or after that oil was put in it. I have used Techron, and I have used RedLine SL-1, during that last 2 years.

I wonder if any of those contained Lead?

The jugs for the gasoline are all plastic.
 
BTW, 2001 was the year the Impala had metal or plastic gas tanks. The Impalas made in the beginning of 2001 had metal gas tanks. The ones made at the end of the year had plastic gas tanks. Our Impala has a plastic gas tank.
 
No the mentioned fuel system treatments do not contain lead. But the only two fuel system treatments that I have not seen a spike in lead when used is Techron and Valvoline Synthetic Fuel System Cleaner. Some solvents do not react well with the lead and other soft material and will show increased wear in soft bearing materials.
 
Originally Posted By: dave1251
No the mentioned fuel system treatments do not contain lead. But the only two fuel system treatments that I have not seen a spike in lead when used is Techron and Valvoline Synthetic Fuel System Cleaner. Some solvents do not react well with the lead and other soft material and will show increased wear in soft bearing materials.



So for fuel system treatments I should use Techron, and no longer use RedLine SL-1?
 
I have been using Red-Line SL-1 at the suggested dose. According to the person I spoke with at RedLine start by putting a whole bottle in the gas tank, and run that until it is low. Then add 4.45 mL per gallon with each fill up. I did the whole bottle, and have gone through three bottles via the 4.45 mL per gallon using a plastic graduated cylinder to measure the RedLine SL-1 that I put in at the pump just before each fill up.

Maybe I should forget about RedLine at each fill up and just dose with Techron once or twice a year?
 
If you check the numerous late model GM v6 UOA's on here weight does not seem to matter, but there is definitely a trend for these engines to shed metal. More or less depending on the oil brand used. The lowest metal numbers were PP. IMO they are picky. Suggest you switch to PP 5w30 and take another UOA at approx the same time.
 
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