jbaj007, I thought the risk was worth taking. So far the responses haven't been too brutal.
haasman, I think it is a very good assumption that the various Mobil 1 grades have similar additive packages. I assume that Delvac 1 has additional detergents and TBN additives.
A blend of 2 materials, one with more additives and one with less, you will come out with something somewhere in the middle.