Guys, this is first winter on 4runner for me. What an amazing car. I did changed tires to revos, but what a car! I shipped car to Armenia and we have quite a snow here. No problems on a snow at all, I do not when need to use 4LO, even in 4HI car climbs snowy and icy hills without any problems. I tried lock the differential today, definitely feel more power and predictable handling in a deep snow, but with 4HI it handles as well. I am new in 4WD and cant really understand when to use what. In which cases I really need to lock the differential or use 4LO?