What oil do you run?

[tdrive0001]

[QUOTE=Roush PSD Interceptor;2358]Rotella 15w40 + 2 quarts Lucas Synthetic Stabilizer, Motocraft FL 1995 and one 12oz bottle of Prolong in the HPOP.
I ran full synthetic last change and will switch back this change.
I always gauge the condition of the dipstick as an indicator of the deposits left behind by inferior oils.
If I can't see the cross hatches on the dipstick thru the oil then it is dirty enough for a change.

My uncle is the shop steward/foreman for Cummins Crosspoint LLC, Cross Lanes, WV.
For 40 years he has worked there.

He says they used Valvoline with the ultraviolet dye marker for break-in oil on the larger engines like the QSK70
at that rebuild shop.
IDK maybe they switched to Delo 400 since he told me that.

We're talking apples and oranges there... the QSK 70 is a full blown industrial engine. I can see the use of oil dye in those. The ISB was initially a light industrial/ equipment engine that was adapted to the automotive platform.