Different?

I don't know.
But the 2.6 was originally designed as a farm equipment deisel, and modified through many iterations to even become the turbo in the Starion.
I bought mine new in `87, and used many 10w-40 oils (whatever was cheap!), until it began chattering on the top end. The more I learned about the engine as it aged, the more I looked at the higher weight oils. The Castrol 20w-50 helped the chatter a lot, but the 15W-40 was better. If you check the running oil pressure you'll notice it runs ~80 PSI, and for most engines, that's petty high. Watch that pressure on a freeway run, or any extended drive, and you'll see it drop as the oil heats up (= viscosity breakdown). This is where the Castrol 15W-40 diesel rated is superb, as it maintains pressure best, with very little viscosity breakdown between oil changes.

The parrafin based business will not be related to the chatter, but it's a concern IF the oil is not changed regularly.

At the very least, try the advice of some of us long-time 2.6 owner and use a good filter and the Castrol.