Okla. Stat. tit. 47, § 11-602
No vehicle shall be turned so as to proceed in the opposite direction upon any curve, or upon the approach to or near the crest of a grade, where such vehicle cannot be seen by the driver of any other vehicle approaching from either direction within five hundred (500) feet.
Added by Laws 1961, HB 556, p. 381, § 11-602, emerg. eff. July 28, 1961.