J.rob, wouldn’t highway speed cause lower oil temps? It doesn’t take much power at all to cruise the highway with all that nice cool air to flow through the engine bay, across the oil pan, where oil gets cooled the most.
idling at a stoplight would heat the oil up much much faster.
I wonder why the builder put the HV pump in and tell him to run 20w50. Must have been with reason. High bearing clearance, shaft style rockers, race use, something.
Another thing to check would be the filter again. If it’s getting clogged, pressure indication will lower. Cut the filter you have on now open and see what’s going on.
