2018 Chevy Duramax L5P - 12,500 miles 43,250 miles total - Oil not changed

wwillson

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This is HPL 15w-40 that now has 12,500 miles on the oil. The TBN is still 13.6 after 6 months and 12,500 miles. I didn't change the oil or filter and probably won't until I get another 5,000 miles. The soot is at 0.6% and doesn't appear to be causing any wear. I have not been able to find a statement by GM on what the soot limit is for the Duramax.

Sample Information
Sample Date25 Apr 20191 Sept 201901 Nov 201908 Jun 2020Aug 2020Oct 2020
Machine Age miles13,00019,60025,30030,75037,80043,259
Oil Age miles5,5006,6005,7005,4506,40012,509
Machine Time hours3204755907348861000
Oil Time hours120150119144152266
Filter Age miles5,5006,6005,7005,0006,40012,509
Oil Changedyesyesyesyesnono
Filter Changedyesyesyesyesnono
BrandDeloDelvac 1Delvac 1Delvac 1HPLHPL
Viscosity5w-405w-405w-405w-4015w-4015w-40
Wear Metals
Iron205234202342
Chromium000<1<1<1
Nickel000000
Titanium0000<1<1
Silver000000
Aluminum10984413
Lead300024
Copper397356691763167
Tin113110
Antimony0000<1<1
Vanandium0000<10
Cadmium00000<1
Additives
Boron737710291197138
Barium000000
Molybdenum0465347604561
Manganese000<1<1<1
Magnesium74610131040894471482
Calcium134811461159100036543786
Phosphorus741107211171030870866
Zinc81113451353112010841032
Contaminants
Silicon25221291314
Sodium244237
Postassium423711545
Fuel %<11.7<1<1.0<1.0<1.0
GlycolNegNegNegNegNegNeg
Soot%0.10.20.10.30.30.6
Fluid Condition
TBN5.147.018.0711.714.313.6
Viscosity15.313.213.413.514.714.61
 
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Iron looks nice and linear, from the June 2020 & Aug 2020 UOAs to this latest one.

What is your take on the copper? If you double 63 (because you drove twice as far this time), you get 126, not 167. Given that you've stated that you want to go 5K more on this oil, obviously you are not alarmed. Is it because 167 is still within the norm for this engine, in terms of ppm/thousand miles?
 

wwillson

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This is why I'm not concerned about the copper trend:


I expect the copper to start trending down soon.
 

wwillson

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That TBN is crazy high still, did you add any quarts throughout the 12.5K miles?
No consumption and no top-off oil.

HPL formulates their HDEO line to have alkalinity (TBN) that starts high and stays high. It's more expensive to formulate and supports extended drain intervals. If you're going to run HPL's HDEO line, it's silly to dump the oil at short intervals.
 
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You’re probably going to have to get the ear of an engineer at Isuzu or GM. Might not be published yet on an L5P.

At 0.6% you’re not there yet. To me, if there was excessive soot in the oil you’d see it in wear metals.

Personally I’d change it at 1% if it was my Truck. I’m sure I’m on the conservative end of it. IMO over 2% will affect engine wear.

I’m curious how this oil would fare in a 6.7 PSD.
 
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wwillson

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At 0.6% you’re not there yet. To me, if there was excessive soot in the oil you’d see it in wear metals.
I don't want to get to the point where we see excessive wear.

Personally I’d change it at 1% if it was my Truck. I’m sure I’m on the conservative end of it. IMO over 2% will affect engine wear.
You are in agreement with Blackstone's recommendation. However, some class 8 truck engine manufacturers will allow up to 5%, which I think is high. The 5% could be a recommendation on "will it cause engine failure before you trade it off?"

I’m curious how this oil would fare in a 6.7 PSD.
I would say fabulously.
 
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Goodness !!!
I thought RL has some crazy amounts of Ca and moly. This stuff is off the charts for HDEO !!!
 
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That TBN is impressive. I don't think I've seen anything quite like that before. I'm running the same oil in 5w-20 now with just shy of 10k miles. I'll likely take a sample of it this week.
 
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