Just a little FYI if you do run a 15/40 designed for Diesel engines they do have more of a detergent in them. Not a bad thing but I'd suggest swapping the new oil within a couple thousand miles as it will clean some junk in the engine.
What he said^ I'd let it warm up a few minutes before driving if it's really chilly but the rest of the world runs just fine on thicker oil. I've read enough pressure and oil threads in my life to boggle the mind but from what I understand the thinner weight oil called for in the USA FSM has...
Also at 200k plus I would highly recommend a thicker viscosity oil. My old 80 with 170k on the clock had much better pressure running good ol rottela 15/40. Your tolerances have increased with age and mileage, your not going to hurt it IMHO
My situation was different than 99% of other fellow mud members. Ultimately I handed the project over to a real professional in the 1FZE field after two attempts at rebuilding. Check your crank for the proper torque setting. Verify pressure with an aftermarket gauge whether that means just...