When driving a manual transmission truck on a long, steep downhill grade, what gear should you use?

When driving a manual transmission truck on a long, steep downhill grade, using a lower gear than you would for climbing the hill is essential for maintaining control of the vehicle. Shifting to a lower gear enhances the engine's ability to slow the truck down through engine braking. This is crucial for preventing brake overheating, which can lead to brake failure.

When descending a steep incline, gravity and momentum can significantly increase the speed of the vehicle. By using a lower gear, you can take advantage of the engine's resistance to help decelerate the truck without relying solely on the brakes. This method not only helps maintain a safe speed but also conserves brake life, as continuous braking can lead to overheating and reduced braking effectiveness.

Using a higher gear or the same gear as you would on flat terrain does not provide sufficient engine resistance during descent, while not changing gears entirely overlooks the need for engine braking altogether. Therefore, selecting a lower gear is the safest and most effective approach when navigating steep downhill grades in a manual transmission truck.