[muff34]

What is the rpm at when idling? How`s the oil pressure when you are driving down the highway is it the same as before this started? Do you hear the lifters ticking when it is idling ? . Ask your grandfather if he can take the oil pressure (electrial sensor) sending unit out of engine and put in a mechanical oil pressure gauge to test pressure. If he does not have a mechanical oil pressure gauge ,He probably has a buddy that has one. Good Luck