Still don't know for sure what happened to scuff all 6 pistons, but closer! The machine shop put each tube in an individual baggy, and labeled them to which cylinder. I got home, and can see through each tube. I phoned them, and they swear up and down there was a 'whiteish, papery material, in all of them. I said, ok, maybe in transit, they fell out and are in the baggy. Still can't find anything. Up until then, I never paid real close attention to the pistons. But now, looking at them, I'm wondering. My thoghts were that if I overheated the exhaust, the piston heads would show something. The heads are real good. Same with the skirts, except for the obvious scuff grooves. The part that gets me is, the skirt, between the head and the first ring looks terrible. I initially put it off as carbon, but upon closer inspection, it's not. I'm now thinking they started melting at that spot. (if I had a camera, it post pictures) Is it possible taht the incoming intake air kept the piston head cooler, the piston tubes were never plugged, thus keeping the bottom of the skirt cooled, but the top portion of the piston head/skirt being the part that would retain the most heat? I'm really leaning at exhaust overheat to now be the cause. At any rate, my advice is to USE THE FILTER RECOMMENDED, and watch those exhaust temps. There is no doubt now, that those 2 things are at the top of my priority list!!

 

I was using the Mopar 15w40. I was using Fleetguard filters, but it was the LF 3349, which is for the older under-valvers. The 24 valves use a different filter. I've pretty much resigned myself to overheat as the cause.

 

If you find the original '5.9 has crapped out' post, it gives all the info. It was too long to re-type. But, I was going up the Coquihalla Highway in the B.C. Rockies. The climb out of Merritt is about 10 KM's long. I was pulling about 7000 lbs, down in 5th gear and about 2500 RPM. My EGT's were around the 1000* mark. I had been that high before, but probably not for this long. My probe is after turbo, so I know I was at the limit, obviously over!