Why would the oil pressure go from about 40 up to almost the red lineit on a dodged 4x4 with a 5.2?

Its because your head gasket blew, filling your crankcase with coolant, diluting your oil, making it pump oil much faster. Can also be caused by a faulty plenum pan gasket leaking.This can cause an erratic oil pressure.The gakets break and will cause oil to be consumed through the p.c.v. valve into the intake.This gasket is located and mounted to the intake on the bottom side.