Questions on oil

My last truck was a Cascadia w/dd15. I changed the oil every 50k until I put a million miles on it then every 35k. In all the years I may have added 4 gals of oil between oil changes ever. So if your loosing oil after 15k I would say you have a problem.

 

Oil changes at 15k vrs 50k is like spending an extra $500 every 50k. I guess that's only .01¢ per mile but in a game of pennies it adds up.

 

I go about 20k with semi synthetic Mystik.

 

Actually that's normal.
Oil does break down and engines will start to burn it faster the longer it's left in the crank case.
IMHO 50k oil changes is just retarded.
I change mine at 15 thousand and it just starts use more the closer to 15 it gets.

Completely normal , you have nothing to worry about.
Some oils break down sooner then others tho , so you could try switching brands to see if it helps.
In my experience rottela broke down faster then delo so I stick to chevron delo 15/40

 

You may think it's retarded but it is the recommended oil change interval on the DD15s that are driven more then 60k miles a year. As the OP is near the 100k a year mark he would fall into that category. His problem could be very simple like not using the manufactures specified oil.

 

Recommended or not , I would never run it out that long. But like I said that's just me. There is a local peterbuilt dealer here in town that I'm perty close with the shop Forman. They have been doing lots of inframes on ISX cummins engines at around 800,000 mark.
They open them up and just wore out.
They blame it on the extended oil drain intervals...........