Hello everyone, I just put an order in for a 2004 Chevrolet Express 3500 Cargo van and it will have the 300 hp Vortec 6000 V8 engine in it. I will be using dino oil for the first 2 oil changes and i'll be switching to synthetic after that. I'll be doing a lot of miles (30k-40k/year)and want to assure myself i will get the most mileage out of this engine. What synthetic oil should I use for this engine? Thank you.