To drive safely on a **long downhill slope**, it is advisable to use **low gears**. This is because low gears allow the engine to help control the vehicle's speed without the constant need to use the brake.

- **Using low gears** helps maintain control of the vehicle, as the engine acts as an additional brake. This is especially useful on long descents, where excessive use of the brake can cause overheating and loss of effectiveness.

- **Avoiding excessive use of the brake** is important to prevent brake wear and overheating, which could lead to dangerous situations.

- **Not driving in neutral** is crucial, as in this position the engine does not help to brake and control over the vehicle's speed is lost.

In summary, by using low gears on long descents, safety is improved and the risk of brake problems is reduced.