Drain the oil. Remove the spark plugs and valve covers. With the pan still under the car, douse the valvetrain with a light oil (5w30), and let it soak for about an hour. Squirt some oil into each cylinder through the spark plug holes. Let this sit for an hour also. Now fill the car with oil.
Hand crank the engine using a breaker bar and the right sized sprocket from the crank pulley. Several times. If things seem pretty free, re-install the old plugs (so you don't foul new ones), and try to light it off. If you get it going, change the oil after it'* run for about an hour. Then change the plugs.