2024 Chevy Tahoe LM2 Duramax 5,550 miles/114 hours on oil - 20,650 total miles/422 total hours - HPL 5w-30 Dexos D

[wwillson]

This is the first sample of HPL 5w-30 Dexos D in this engine. The back story of why I asked David at HPL to blend a 5w-30 Dexos D is the volatility of the light base stocks in the 0w-20. GM runs this oil very hot, around 240-255°F, and the engine consumed 1 quart in 10k miles. With 0w-20, I tried manually shifting into a lower gear as the EGTs went above 1,100°F to lower the EGTs and piston temperatures and it still consumes oil. The base stocks in the 5w-30 should be about 1/2 as volatile as the base stocks in the 0w-20. In 5,000 miles of 5w-30, the consumption is 1/4 quart, so the premise that the 5w-30 is 1/2 as volatile seems correct. I haven't manually shifted with the 5w-30 to keep the EGTs down, I just let the computer do what it wishes and overall the 5w-30 has dealt with higher EGTs.

The wear metals have come down nicely from the wear-in between 0-15k miles. There is a video of the PPE filter run for 12k miles in the revious UOA. GM sure doesn't do a great job of getting the machining chips out of the blocks. I added 1/4 qt and the TBN increased slightly. The oxidation is non-existant, even with the oil running so hot in this engine. That's a testament to the quality of the base stocks and the anti-oxidants in the oil. The soot is already at 0.6% and I suspect the soot level will be what causes me to condem this oil as the miles increase. The viscosity increased from 9.9 to 10.1, which is insignificant and seems to correlate with the very low oxidation. I'm very happy with the decreased volatility of the 5w-30, but we might run a 15w-40 Dexos D blended for low valatilty just for fun. We'll see how the 5w-30 does over the course of this OCI.

Previous UOA here

Google Sheets UOAs

Sample Information
Sample Date	5/4/2024	5/5/2024	9/22/2024	10/13/2024	01/06/2025
Machine Age miles	3,000	3,050	13,690	15,125	20,650
Oil Age miles	3,000	50	10,640	25	5,550
Makeup oil quarts	0	0	1	0	0.25
Filter Age miles	3,000	50	10,640	25	5,550
Oil Changed	yes	no	no	yes	no
Filter Changed	yes	no	no	yes	no
Brand	OEM	HPL	HPL	HPL	HPL
Viscosity	0w-20 Dexos D	HPL 0w-20 Dexos D	HPL 0w-20 Dexos D	HPL 5w-30 Dexos D	HPL 5w-30 Dexos D
Wear Metals	(ppm/1k miles)
Iron	38(12.7)	7(0)	69(5.9)	9(0)	29(3.6)
Chromium	<1	<1	1	<1	<1
Nickel	<1	<1	<1	0	0
Titanium	<1	<1	0	0	0
Silver	6	<1	5	1	2
Aluminum	4	3	11	7	12
Lead	<1	<1	0	<1	0
Copper	10	2	93	12	154
Tin	2	<1	4	<1	7
Vanandium	<1	<1	0	0	0
Cadmium	<1	<1	0	<1	0
Additives
Boron	40	106	70	89	74
Barium	3	2	1	0	0
Molybdenum	27	71	74	63	80
Manganese	2	<1	2	<1	1
Magnesium	15	876	1065	847	1018
Calcium	1781	1167	1387	968	1152
Phosphorus	879	798	769	664	696
Zinc	927	821	907	762	832
Contaminants	(ppm/1k miles)
Silicon	104(35)	23(0)	44(2)	14	18(0.7)
Sodium	2	0	2	2	2
Potassium	5	3	2	0	2
Fuel %	<1	<1.0	<1.0	<1.0	<1.0
Glycol	NEG	NEG	NEG	NEG	NEG
Soot%	0.2	0.1	0.6	0.1	0.4
Fluid Condition
TBN	7.9	12.54	11.21	13.15	14.03
Viscosity	8.2	8.9	9.1	9.9	10.1
Oxidation	11.2	0(30)	5.7(35.7)	0(32.1)	2.1(34.2)

 

[OneLonelyBurrito]

Any idea where the copper is coming from? Other than the copper, everything looks great. It sounds like you do some towing with it since you’re hitting 1100F EGT often, if so I wonder if that is contributing to the copper.

 

[edyvw]

What is with these copper oscillations? Oil cooler?

 

[twX]

Elevated copper combined with tin might suggest that it's coming from bronze parts, which are mostly copper but usually contain around 10% tin. Bronze can sometimes also contain a lot of zinc. Zinc is elevated on the used oil samples, as is the Zinc/Phosphorus ratio. Blackstone universal averages for copper and tin for this engine are 5 ppm and 1 ppm.

Turbocharger journal bearings are commonly made of bronze. Rod and main bearings can can contain bronze as well, but only in the intermediate layer, which shouldn't be wearing at all. Maybe some the copper used in the oil cooler has a significant amount of tin as well, but I haven't seen this much tin on UOAs from other engines that have high copper from oil coolers.

If the copper is coming from the oil cooler, but the tin isn't, then where is the tin coming from? The only other significant source of tin that I'm aware of would be tin-based overlays on rod or main bearings. I think it's more likely that the copper and tin are from the same source though.

If this oil is causing copper to corrode from the oil cooler, that's probably inconsequential. If it's doing the same thing to a bronze turbo bearing, that might be more of a concern.

 

[wwillson]

Any idea where the copper is coming from?

My guess is the oil cooler, going to look into that.

It sounds like you do some towing with it since you’re hitting 1100F EGT often, if so I wonder if that is contributing to the copper.

Almost no towing. This 3.0L cranks out a lot of torque, around 460 pound-feet. Ascending grades at 75 MPH on the interstate takes a lot of power and makes a lot of heat, 1300°F is common.

 

[OneLonelyBurrito]

My guess is the oil cooler, going to look into that.


Almost no towing. This 3.0L cranks out a lot of torque, around 460 pound-feet. Ascending grades at 75 MPH on the interstate takes a lot of power and makes a lot of heat, 1300°F is common.

Got it, I guess I didn't think it would push EGTs that high while driving around without the addition of a trailer.

 

[dnewton3]

Elevated copper combined with tin might suggest that it's coming from bronze parts, which are mostly copper but usually contain around 10% tin. Bronze can sometimes also contain a lot of zinc. Zinc is elevated on the used oil samples, as is the Zinc/Phosphorus ratio. Blackstone universal averages for copper and tin for this engine are 5 ppm and 1 ppm.

Turbocharger journal bearings are commonly made of bronze. Rod and main bearings can can contain bronze as well, but only in the intermediate layer, which shouldn't be wearing at all. Maybe some the copper used in the oil cooler has a significant amount of tin as well, but I haven't seen this much tin on UOAs from other engines that have high copper from oil coolers.

If the copper is coming from the oil cooler, but the tin isn't, then where is the tin coming from? The only other significant source of tin that I'm aware of would be tin-based overlays on rod or main bearings. I think it's more likely that the copper and tin are from the same source though.

If this oil is causing copper to corrode from the oil cooler, that's probably inconsequential. If it's doing the same thing to a bronze turbo bearing, that might be more of a concern.

My guess is that the Cu is coming from both the oil cooler and also the turbo bushings. The tin obviously would only be the bushings. Unfortunately, we'll never know how much (by % of the total) can be attributed to the cooler vs bushings; no practical way to tease out the individual contributions from the whole. This phenomenon is known from the larger 6.6L Dmax engines as well; it is generally accepted to be the chelation of Cu due to chemical reaction to the additives in the fresh oil(s). When the OCIs mature, the rate will drop off, typically.

No matter; it's just interesting side-line talk. Overall, a decent UOA.

 

[Bighorn2500]

Would having them blend a cold climate 10w30 dexos D oil be an option? Just wondering if it would provide just as much protection as a 15w40 in the little Duramax. Can a dexos D also be cold climate? I saw the Colorado climate which can get cold in your location.

 

[fantastic]

Copper past severe oil contamination levels according to some labs condemnation levels. My speculation is both wear since Tin has doubled as well, like @twX mentions, & copper levels due to oxidation from higher sulfur levels in these oils. Thought I saw recently there was like x4 times more sulfur in these oils than a typical off Mobil product. Probably can't find them again but remember seeing that difference recently posted here. Regardless Cu seems to be severely elevated when compared to your original sample. Iron & silver seem to be coming down.

 

[wwillson]

This phenomenon is known from the larger 6.6L Dmax engines as well; it is generally accepted to be the chelation of Cu due to chemical reaction to the additives in the fresh oil(s).

This is my thought because of our prior knowledge of the Duramax and the lack of any other wear metals above normal.