I see on the receipt that they used synthetic oil and this truck (Dodge V6 Dakota) has. Right after they did the change I started noticing that the oil pressure guage would drop to. I can't imagine this to be a oil viscocity issue.
Almost all other manufactures oil pressure gauge just reflect an average pressure
One thing I noticed is that the oil pressure seems to read a bit lower than before,. I would encourage you to use a synthetic, as it will prolong the life of your turbo, and help. . The heavier weight oil does raise the oil pressure.
Yes thicker oils will increase oil pressure, but will reduce engine. .. oil pressure when I switched from 5w30 conventional to 5w30 synthetic not .