Just got a new (to me) 4runner limited 02. I've read in the manual to run it in 4HI (center diff unlocked) for at least 10 miles a month to lubricate things. No problem there.

I also have read online to run it 2-3 times a year in 4 LOW...but is this enough?

Will doing it on gravel be good enough for 4LOW and to not take any turns and just go in a straight line for a minute or so? Or how long should I run it in 4low to make sure it all works and stays lubricated. Last thing I want to be is stuck and needing 4 low (which is rare, but better to have it working)

Winter is not here yet.

Also, should I engage the center-diffs locks now and then (of course on slippery service) to lubricate the lock mechanism.

thanks all!