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At highway speeds, YES!
There is no need for the fan to run while traveling at highway speed. There is plenty of air flowing through the radiator at high speeds to keep the system cool. The only time it will work at highway speeds is when the A/C is on.
Different weights and traveling in opposite directions.
Different weights and traveling in opposite directions.
Transmission needs an overhaul
If by this you mean only "hot heat" when drive at highway speeds likely thermostat bad and/or almost stuck and takes long time warm up from high engine RPM during highway driving.
Overdrive is an extra gear assembly in the transmission that allows the engine to run at a lower speed (lower RPM) when you are travelling at higher speeds on the highway or freeway. For example, if I am driving my 1995 Explorer at 62 mph in drive, the engine runs at 2800 RPM. If I am driving at 62 MPH in overdrive, the engine runs around 2100 RPM.
Overdrive lets the engine run slower at highway speeds. This saves on gas.
A car's engine will turn higher RPM (rotations per minute) on the highway due to the increased speed needed to travel at highway speeds. A car does not need to have it's engine spin at the same RPM level on the city street as it does on the highway.
It would shorten the life span of the engine some.
Me
.38-.43 with .40 ideal for idle and highway speeds