I believe when the GM engineers developed the software that controls the engine they had many requirements, including fuel economy and quiet operation. At low RPMs you can barely hear the 3.0L or the 6.6L diesels, but drop a couple gears, like I do, and you can definitely hear them. I choose to trade off quiet operation (10th gear) for lower EGTs (8th gear), evidently the GM engineers did not accepts this trade off, but they do publish and accept that oil consumption is the norm while towing, driving fast, etc. The fuel economy will be slightly less, because of increased friction from increased engine RPMs, very slightly. The ECM is programmed exactly as GM wanted it.
Lowering a gear or two and increasing RPMs to lower EGTs is common with line-haul trucks. It physics, the more power strokes you have over a duration of time with the load steady, the EGTs will be lower.
Thanks - I didn't know aluminum has these characteristics.
I don't hear of high mileage factory power Duramax engines with piston failures. But we do see increased aluminum in oil samples from engines that work hard and have aluminum pistons. Keep in mind that the 1300+ EGT doesn't mean the pistons are 1300 degrees. They would be melted blobs if they got that hot. Oil squirters, squirt oil into the piston oil gallery that goes in one side of the piston crown and out the other. The circulating oil removes a large amount of heat. I think the 6.6L Duramax pumps over 10 gallons/minute through the oil squirters.
I disagree. I've written about the torque race and my opinion is that oil consumption can be highly correlated to the high heat in these high specific power engines.