I worked for old man murphy at murphy cheap motor freight in the 60s he took 5 new macks with old maxidine and 5 more just like them. He ran them 365 1,000 mile round tirps mpls to chicago in a year never shut off the first 5 and did normal maint on the other 5. HE MODIFIED THE RUN FOR A YEAR WITHOUT SHUTTING OFF to have a glass sight tube to check the oil.
Pulled one of each engine down and came to opinion that rotella would run 380,000 miles just fine. Was funny to see mechs change tires on a tractor still idleing... Funny thing was the way those old rigs leaked none of the original oil could have been left after changing filters every two months....
I have 92,000 on an isl 400 and it is just about as happy a pig in mud...