I would try adding a can of Seafoam to your van's oil
My electrician bought a used Toyota Camery for his wife.It used about 3 quarts between oil changes,which for a Toyota is excessive.He added seafoam to the oil a week before it's next oil change.
Oil consumption went to almost not having to add oil between changes.He was happy with the result.
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews