Crankcase Oil Preference

I did a search and didn't see a whole lot on this subject.

I'm needing to change the oil in a couple of my D2's and I have no idea what is currently in there, except it is black as coal. Now the Book says to run SAE 30 weight CO and also mentions Series 2 Superior Lubricants as most satisfactory. In my other diesel tractors and Cummins diesel pickup I am running either Delo 400 15-40w or Rotella 15-40w diesel grade oil, but these are much newer engines.

In my younger days, I once bought a 1965 Datsun pickup that was about fifteen years old. Being conscientious, I immediately did an oil change to my favorite Castrol 20-50w detergent oil. But soon after, to my dismay, the truck started leaking oil severely. Turned out the PO had been running non-detergent oil in the truck and over time it had built up 'dirt seals' which the detergent oil dissolved, hence the leaking.

So is there any risk that something like this could happen to my D2's if I put today's modern detergent oil in them?

On another topic, some car enthusiasts with pre-1990 cars recommend adding ZDDP to today's modern oils. They say that today's oils are 'watered down' on wear additives and that causes more wear on older cars. The only additive I have used is called "Restore" which helps seal piston rings, and it does a good job increasing compression in older engines. So comments on these additives in old Cats would be appreciated.

i just use tsc diesel fleet 30w. workes fine. good luck.

I use Delo 400 15W40

Kevin

D2 5U13247 Direct electric start, #44hyd, 2S blade, Hyster D2N

I use Rotella 30W in my tractors in Summer.
I use Rotella 15-40W in my D2 with a Synthetic in the Pony in case it is called out for Snow removal duty in winter.
I use ZDDP in my Ford Model A.