GC 0w-30 5.3L

[CONMCK]

Check out the UOA from my last GC interval in the Used Oil Analysis, Gas Engines. After 6300 miles/10200km judging by the viscosity, I'd say the oil was at the end of it's service life, comments??

 

[vad]

On what basis did you come to that conclusion?
Just a minor viscosity change?
The sample looks very good judging by the previous UOA's.
Like Bruce suggested, the next time opt for the TBN.

 

[CONMCK]

So at what point would a person change the oil based on viscosity only?.....13....14...?
I didn't bother with TBN only because past TBN in this engine (2 results) always showed plenty, 5.5-7.7.

 

[bretfraz]

I don't see a big problem. No numbers seem to stand out. Lead is 18 vs. 17.44 avg. Vis at 12.93 is no problem, especially with an engine that likes oil a tad on the thick side.

Having the TBN is an important data point so its hard to tell what the oil's condition really is without it. It would have been especially interesting after this current OCI, the longest you've ever gone.

Your avg SI is 28 so the last two OCI's seem high but are right in line with your avg. Still, whatever you can do to lower the number would be good.