Only use 4wd when the roads are slippery (i.e. Snow or ice). On dry pavement driving in 4wd could/will DESTROY the transfercase. Even in snow and ice…MOST of the time I’m in 2wd. I just slow down. The only time I’ll put it in 4wd is if the snow is very heavy and not plowed (this does happen during snow storms sometimes). When I do shift to 4wd on the highway it’s because the weather is very bad and I’ve already slowed down to about 30. I can shift into 4wd at any speed, but if it’s bad enough to be in 4wd then driving at 65mph is NOT a good idea.