Okla. Stat. tit. 47, § 47-11-303: Overtaking a vehicle on the left - Signal

The following requirements shall govern the overtaking and

passing of vehicles proceeding in the same direction, subject to

those limitations, exceptions and special requirements hereinafter

stated:

1. The driver of a vehicle overtaking another vehicle

proceeding in the same direction shall pass to the left thereof at a

safe distance and shall not again drive to the right side of the

roadway until safely clear of the overtaken vehicle.

2. Except when overtaking and passing on the right is

permitted, the driver of an overtaken vehicle shall give way to the

right in favor of the overtaking vehicle on audible signal and shall

not increase the speed of his vehicle until completely passed by the

overtaking vehicle.

3. Every driver who intends to pass another vehicle proceeding

in the same direction, which requires moving his vehicle from one

lane of traffic to another, shall first see that such movement can

be made with safety and shall proceed to pass only after giving a

proper signal by hand or mechanical device.