Alrighty boys, my 5.9 has 111k on it. Recently changed the plenum and added the new thicker plate. Shortly after that I added new plugs and scoped the cylinders and saw coolant. Figured the junk stock heads had a hair line crack, so put new eq heads and did the whole job over again. About 1000k after doing the work I checked my oil, down about 1 quart. I am running mobil1 synthetic 10w-30. I scoped the cylinders again 1 and then went to 7 & 8. 7 & 8 are starting to show carbon on top again 1 was ok. I cleaned the crap out of all the pistons tops when I installed the new heads. I have a new Mopar PVC.

This week I installed an oil catch can, and took a long trip around 300 miles back and forth and towed on the way back. I already have oil in the catch can, I would say maybe 2 oz from the bottom of a soda can. Truck feels fine and strong when towing. Finding oil in the catch can is a sign of blow by, but I am still wondering since I saw the back cylinders carboning up if again its the damn F'ing plenum gasket. I used locktite on the bolts and torqued to spec when I redid the job. I looked inside the plenum and saw a bit of oil on the back wall with my scope cam. But then again maybe the oil from the pvc has a natural tendency to land on the back area which would explain what I saw in the plenum.

Thoughts?

Another user went down the same rabbit hole as me, 1000k and 1 quart of oil no mention of final thoughts on cause.
https://dodgeforum.com/forum/2nd-gen...um-help-2.html

Picture of 2 of the pistons cleaned earlier in the year.

 

Catchcan -air/oil seperator isgood thing too have on 5.9.It from the PCV valve,they spit alot of oil .Not too worry it's a common thing with these motors.

 

Might do a dry/wet compression test, see what kind of shape your rings are in.

 

Agreed. Dry/wet compression test if nothing else other than to establish the current condition of your rings. The catch can is a good idea always. I had a new Chevy 350 that used 1 qt every 1000 miles from the day it came home and it never got any worse. If the motor is running well with no complaints don't fix it if it ain't broke. Stop looking in the plenum. Run good quality gas and stay with the Mobile 1.