I'm guessing that one modded diesel truck in my town makes more Nox and C02...
You mean CO? Any mods to a diesel wouldn't cause it to put out more CO2, unless it's by way of making more power/burning more fuel.
When I modified my Cummins the fuel economy increased from 13-14 MPG to 17-18 MPG. I'd argue that my CO2 emissions decreased as a result of burning less fuel.
Absolute mathematical certainty that your CO2 emissions went down when your fuel economy improved.
Also, that's a great set of UOA's that show a great improvement in oil life after deleting the DPF.
Wear metals went down, the viscosity stayed in grade, TBN retention increased, and flashpoint improved.
A_Harman can you help me understand / point out where the wear metals went down? It looks like Fe and Al stayed around the same but copper came down (usually copper is from the oil coolers).
Also, can we assume wear could be decreased from eliminating fuel dilution? Just trying to learn here, not challenging anyone's comments.
I was looking at the Iron numbers, and dividing them by the oil change miles.
For the first three, the numbers were 43 ppm / 4.83 kmiles, 35 ppm / 4.62 kmiles, and 62 ppm / 8.05 kmiles. This gives wear rates of 8.9, 7.6, and 7.7 ppm/kmile, and an overall wear rate of 8.1 ppm/kmile before the emissions controls were deleted.
For the next three, the numbers were 43 ppm / 8.57 kmiles, 25 ppm / 10.63 kmiles, and 32 ppm / 14.74 kmile. This gives wear rates of 5.0, 2.4, and 2.2 ppm/kmile, and an overall wear rate of 3.2 ppm/kmile after the deletion.
So the overall average Iron wear rate decreased by ~60% from pre to post-deletion. And the last two readings have improved significantly over the first post-deletion UOA. This may indicate the engine is breaking in, and Iron wear will decrease more gradually.
Another factor that may be contributing to the decrease in Iron wear post- vs pre-deletion is the Phosphorous content of the oil the 3 pre-deletion numbers were 743, 904, and 816 ppm, and the 3 post-deletion numbers were 1013, 1095, and 1230 ppm. These numbers indicate a significant increase in ZDDP, which could have been helping post-deletion.