I do use Mobil 1 0w-40 in the winter, resulting in zero difference in
oil
Pressure vs. the Mobil 1 15w-50 the rest of the year
Just want to add that one thing I've learned over the years, is that are very few hard and fast rules as it pertains to ones engine building methodology. In other words, there's more than one "right" way to do things and end up with successful results .
Z