No, you cannot grease the wheel bearings on a 1999 Ford Taurus. The wheel bearings on that model are sealed and pre-packed units. They are not designed to be greased. If you attempt to grease them, you risk damaging the seals and causing premature bearing failure.
Instead of greasing, if you suspect a problem with your wheel bearings (noise, roughness, etc.), the entire bearing assembly needs to be replaced.
