When it comes to traction on slick pavement, gravel roads, snow or off-road, four-wheel drive may be more likely to help keep you moving forward when a two-wheel drive vehicle could slip off the shoulder or be buried up to the axle attempting to get a grip.
This begs the question: When do you use the various modes of four-wheel drive?
Here’s the down and dirty, which will help keep you from having to dig a stuck truck out of a ditch.
Four-High (4H): In high-range four-wheel drive, you can travel at all normal speeds. Engage this setting when you’re on the highway and roads are sketchy – wet, snowy, icy. It’s also good for level, loose-gravel roads, packed sand or mud.
Four-Low (4L): The low-range four-wheel-drive setting is for the serious stuff – deep sand, snow, mud, crossing water, climbing rocks and ascending/descending hills. When you use four-low, keep your speeds low, too (under 40 mph or so), as you’re not actually gripping the road any better but you’re applying more torque to that grip.
Automatic Four-Wheel Drive (Auto 4WD): This is a modern convenience that allows you to effectively “set it and forget it.” In this setting, the automobile monitors tire traction while in two-wheel drive and automatically shifts into four-wheel drive when one of them begins to slip. Use this setting when roads are variable, such as patchy snow and ice or any other combination of conditions when a tire could slip suddenly.
Keep in Mind: You should never travel in four-wheel drive on flat, smooth, dry roads, as it will damage your drivetrain. Also, remember that four-wheel drive provides more torque and engages all the tires for movement – it doesn’t help you stop. Always travel at speeds that allow you to stop safely, regardless of how well you’re moving forward.
When shifting from two-wheel drive to automatic four-wheel drive or four-high, you can do so “on the fly” – or while traveling at normal speeds. When shifting into and out of four-wheel-drive low, however, you will likely need to come to a stop and wait for the indicator light to stop flashing.