Melt butter in small saucepan; stir in lemon juice, garlic salt, paprika and oregano.
Place chicken in shallow dish; sprinkle with salt and pepper. Pour marinade over chicken; cover.
Marinate for 3-4 hours, turning occasionally. Drain, reserving marinade.
Place chicken, skin side up on grill set 3-6 inches from charcoal that has reached light gray ash stage. Brush with reserved marinade.
Cook 45 minutes to 1-1/2 hours or until tender, turning and brushing with marinade occasionally.