* 4Hi (4-High): This engages all four wheels in high range. It's used for improved traction in slippery conditions like snow, ice, mud, or loose gravel on paved roads or relatively smooth, unpaved roads. It's not ideal for extremely low traction situations or steep inclines. Speed is relatively unrestricted.
* 4Lo (4-Low): This engages all four wheels in low range. This drastically reduces the vehicle's speed but increases torque significantly. It's designed for extreme off-road conditions like steep inclines, deep mud, or rocky terrain where maximum traction and pulling power are needed. Driving in 4Lo on paved roads is generally not recommended due to its low speed and potential for damage.
In short, you shift into 4Hi for improved traction in mildly challenging conditions, and into 4Lo for extreme off-road situations requiring maximum torque and crawling ability at very low speeds. Always remember to engage 4WD only when necessary and follow the owner's manual for proper engagement and disengagement procedures.