FORD 2006 F-150 v.2 - Manual (Page 234)

Engine temperature while plowing
When driving with a plow, your engine may run at a higher temperature
than normal because the attached snowplow blade will restrict airflow to
the radiator.
If you are driving more than 15 miles (24 km) 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 15 miles (24 km) at speeds up to 40 mph
(64 km/h) in cold weather, you will not need to worry about blade
position to provide maximum airflow.
2006 F-150 (f12)
Owners Guide (post-2002-fmt)
USA (fus)
Driving
234