I have a 2000 Lincoln Navigator it get water into the oil as soon as you fill the radiator.
Sorry to tell you this but I believe you have a cracked engine block.
Or badly blown head gasket, or bad intake manifold gasket. HTH. -Jim
Looking for a Used Navigator in your area?
CarGurus has 5,612 nationwide Navigator listings starting at $1,900.
Search Lincoln Navigator Questions
Lincoln Navigator Experts