Hey guys, I know I'm about to open a can of worms here, but which oil do you prefer to run & why ? Both oils carry the same certifications it seems, the Castrol being a thinner 40 weight than the Mobil it seems. The Mobil looks to have more Boron & Moly, the Castrol more Mag. I'm thinking the slightly thinner Castrol will deliver better fuel economy (on a very small scale I'm sure). Just wondering which would be better for a DI Turbo gas engine, or am I splitting hairs trying to choose between these two ?