Hello, I have come accross 10 qts of mobil 1  15W50 for cheap at an estate
sale. I would like to use them up. I plan to add 3 qts of mobil 1 and 2 qts
of dino 20W50.Kinda of a blend. I will add a qt of mobil one and then 1 qt
of dino ,alternately as the moter leaks, and uses the oil.Is this ok,
without changing the  black Mahl filter? It is an old 1.9.Thanks, Roger
Sisler.