The guy who installed my gears said to get on the highway for about 30 miles or so to let the gears get hot then park it and let them cool down completely . I had a 25 mile ride home from his shop and when I got home the diffs were pretty hot ,next morning drove to work and took it easy on it for the 15 mile ride ,they were a little warmer than normal drove home that night and diffs were normal temp. I still took it easy for another 100 miles even drove a couple times to work in 4wd and all was good I have wheeled a few times since with no problems. I have about 4000 miles or so on them now with no problems not even noise and I drive my jeep pretty hard on the street.