I have a buddies truck I swapped a built motor in. I built the truck it was in previously and it didn’t have this issue, but it did sit for about a year before my buddy bought it. If it sits more than ~3 hours it takes 5-10 seconds to build oil pressure on start up, it even tripped the low pressure light briefly once. You can hear the motor chattering til it gets pressure. I know there’s a relief in the pump, 2 in the cooler, and one in the front cover. I hate to go throwing parts at it. Has anyone had this issue or dealt with it and know of a solution. It’s 15w40 and I already tried swapping out the filter. Thanks