New to this porsche stuff, bought my first Porsche only 4 weeks ago as project, and i have a problem with oil pressure. !!!!Boxster 2.5 1998 90K miles. will dump the oil out of her, replaced filter and was going to refill with 5w-40w ? The trouble ive got is at start up all good.. as she warms up oil pressure disapears after about 5 minutes on tick over and puts on oil warning light, i have checked this with an old external presure gauge and drops to 5Lb psi when warm .. 22Lb psi when starting from cold and zooms up to 70psi + when revved Have already checked the pump and both scaenger pumps and all fine.. Cant believe just fresh oil will resolve this pressure issue . ANYONE GOT ANY IDEA`S what next ?

The next thing I would check is the oil pump pressure regulator spring and plunger. There were some older posts about these sticking.