Driving at highway speed in 4x4 high is fine. Doing it in 4x4 Low is impossible.
If the road is bad enough to need 4x4, then use it. If the road is slick, but you still get plenty of traction, leave it in 4x2 mode.
I have driven the wifes 4x4 Explorer in 4x4 mode for many miles when the roads were that nasty. It did fine. Her's is a Auto 4x4 which means if the wheels slip, the transfer case kicks in. If it is going in and out of 4x4 all the time, put it in 4x4 mode.
The only time you need 4x4 Low (What I think Jerry is refering to) is when you need the extra power like climbing a steep hill or decending one to help control the decent speed.
Doing 65 MPH (65/.62=105 KM/HR) in 4x4 mode is perfectly fine.
Personally, I have a 4x2 Trac and never had an issue with traction. Even with 12" (12*2.54=30.5 CM) of snow on the ground, I still got around just fine. Sure I wasn't zipping around like summertime, but I got where I needed to go as well as these FWD cars do.
If it is REALLY that bad you need to put it in 4x4 mode to get up the road (provided you don't live in a snow belt or the mountains) you should get new tires. I find myself putting the wifes Explorer in 4x4 locked for two reasons. 1, to exercise the transfer case and keep everything working, and 2, so I can drive like an idiot.
There is alot of confusion as to what is the difference between 4x2, 4x4 High, and 4x4 Low is.
The difference is really simple.
4x2 means the rear wheels power the vehicle.
4x4 High means it has the same gearing as 4x2, except the transfer case also sends power to the front wheels.
4x4 Low means the transfer case goes through some extra gearing that raises the ratio to provide more power to the wheels. This is used to get better control over uneven terrain and to pull stumps or other vehicles out of the ditch. It is not to be used to drive down the road when the roads are slick. That is what 4x4 High is for.
Tom
