The FWHs are primarily to save fuel, especially on short runs on cold days, when the oil in the diff is thick. On a longer run with the hubs locked, the oil would warm up through being constantly churned, which greatly reduces the consumption improvement.themac wrote: ↑Thu Nov 27, 2014 9:46 amDoes this include having the hubs in the "lock" position? I noticed when I brought my SJ home that she had been driven with one of the hubs in "lock" and one in "free" for God knows how long. I changed the oil on the diff and it doesn't seem like it has taken any damage, the side that hade been on "lock" I couldn't change back first but now after the oilchange and some WB40 on the knob itself it clicks in and out of place without any problems.
I have been wondering though, since not all SJ's was sold with manual hubs at all, if it is recomended to unlock them when you don't drive 4wd? I understand there being extra wear on the front axle and the oil there, but could it harm the axle?
Also as others have said, it reduces wear.
The hubs should be locked at least once every 1,000 miles for a few miles to keep everything nicely lubricated.