My dad has an 07 classic. The low oil pressure light comes on and you have to put the truck in neutral and rev it up so the oil pressure builds. Sometimes it does it when your on the highway running 65-75, then it does it when u slow down or get off the exit. Then it just goes on randomly when ur driving up the road and stop at a light. Its been to the dealer and they say nothings wrong. Any help would b appreciated.