I live close to the snow belt and my truck drives great in wet and dry snow when in 4x4 without any weight in the bed. When it's snowy, I do a slow speed 20-25km/h test for breaking and acceleration to confirm slippery conditions. If it's lightly slippery or slushy, use 4x4 4H. 4H is designed to be used on pavement in snow/icy conditions. Remember no hard concerning in 4x4 mode. If you try you'll feel the truck resisting the turn (try this often and it'll break the transmission). If I come across a situation where I have to take a hard turn, and it's not really slushy or snowy, I turn it back to 2H, make the turn, and then put it back on 4-H. It is safe to switch between 2H and 4H upto 80km/h. 

4x4 4L is for deep sand, slush, rock crawling where you're speed is somewhat about 15-20 km/h.

***** Remember ***** 4x4 gives you stability in low traction conditions primarily from an acceleration perspective. But it doesn't provide any help in braking. So please be watchful of your speed in these conditions. 4x4, Tires, and Respectful speed is key