Hi,just ran about 5k miles on D-1 with no need to add makeup oil. Last summer,on Castrol Syntec 5w-50,I added 1/2 qt. Maybe,it's not too significant.The UOA will give a profile to compare with Syntec
.Is D-1 the better oil for my '99 E-150 Ford Van(4.2L six)with 30K.