A 2000 Ford E-150 van's oil type depends on the engine it has. Ford E-150s from that year came with several engine options. To know for sure, you need to check your owner's manual or the sticker on the vehicle's driver's side doorjamb (often near the VIN). That will specify the recommended oil type and viscosity (like 5W-30 or 10W-40).
Without that information, I can only say it likely uses conventional or synthetic motor oil meeting the specifications listed in the owner's manual.
