Have an interesting comment to add. A DHL leased operator had a diesel cube van that he got towed into the GM dealer due to loss of oil pressure. They told him the motor will need to be tore down and inspected for trouble........big expense.
He ended up buying another cube van seeing his had a lot of miles on it. He sold his old one locally to a guy he new for $1,000.00.
A couple days later he gets a call from this guy and said the van runs fine............was just an oil pressure sending unit.
Nice diagnosis from the dealer.