I have a 1999 4 Runner which I will never buy any other 4x4 except a newer 4 Runner. What are the "rules" for using the 4x4 high gear? We had a lot of snow last night and the highways were plowed but not clear completely. There were some wet areas and slush areas, and snowy areas about 1/2"to 1" deep. I was driving about 45-60mph for about 45min to work. How should I handle swiching in and out of 4x4?