Transmission Operation While Plowing - Ford 1999 F150 Owner's Manual

Driving
If you are driving more than 24 km (15 miles) at temperatures above
freezing, angle the plow blade either full left or full right to provide
maximum airflow to the radiator.
If you are driving less than 24 km (15 miles) at speeds up to 64 km/h
(40 mph) in cold weather, you will not need to worry about blade
position to provide maximum airflow.

Transmission operation while plowing

• Shift transfer case to 4L (4WD Low) when plowing in small areas at
speeds below 8 km/h (5 mph).
• Shift transfer case to 4H (4WD High) when plowing larger areas or
light snow at higher speeds. Do not exceed 24 km/h (15 mph).
• Do not shift the transmission from a forward gear to R (Reverse) until
the engine is at idle and the wheels are stopped.
• If the vehicle is stuck, shift the transmission in a steady motion
between forward and reverse gears. Do not rock the vehicle for more
than a few minutes. The transmission and tires may be damaged or
the engine can overheat.
Do not spin the wheels at over 35 mph (55 km/h). The tires may
fail and injure a passenger or bystander.
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