Diesel oil is 15W-40 most of the time.
Shell Rotella is the most popular brand.
Yes, it is formulated differently from oil for cars and light trucks.
It is higher in zinc, for one thing.
I’m retired and work part time in one of the largest auto supply chains in the nation.
For the last 6 or 8 months Diesel engine oil supply has been sometimes spotty. We serve a lot of loggers, heavy equipment operations and heavy equipment mechanics.
We go through a lot of it every week.
I bought three oil changes for the wife’s diesel Silverado and put them out in the barn.
Not only diesel oil, but all trucks since 2010 have an emissions system that requires a fluid called DEF. This is getting in short supply, the major manufacturer of urea, the main ingredient, is Russia. The US ranks #4.
The computers in these trucks are programmed to shut the engine down if there is no DEF in its on board tank.
You think there’s shortages now? Just wait.