See owner's manual, it's surely spelled out in there. If you don't have one, Haynes or Chilton's will have the schedule in them, $15 and you can also use it to help with some minor repairs.
You can, just to get the lube splashing around in the front diff. Maybe once a month.
Avoid turning on dry pavement while in 4x4 at all costs. That's about the biggest thing.
On Maintenance... Some Chevy dealers have a 4x4 'fluids change' package for $120 or so.... Tranny Fluid & Filter is extra.... Rotate the tires at least once a year or the Fronts will wear & 'Hum'... Change the Fuel Filter every year or so....
Be aware that some of the 4x4 push buttons have 'cool solder joints' & Service 4x4 warning comes on... Resolder or See Dealer....
Test 4x4 mode occasionally & CORRECTLY!!!!
Do shift into or out of 4x4 Lo only in NEUTRAL and when stopped !!! And sometimes the 460LE tranny sits & looks at U at a green light for 3 seconds.. Then goes....
I don't know about the michelins but if you want a great tire get the BF Goodrich All-Terrain TA's. You will not regret it. BF Goodrich now has their Adventue Assurance program where they will come rescue you offroad or on if you ever get stuck due to loss of traction. 285/75-16's fit my Yukon with no lift.
Carry an extra set of grill running light bulbs.... Practice on taking the headlight 'snap' rods out for installation... You'll need 1 or 2 small flat screwdrivers to pop the bulb sockets apart..
On the rear bulbs... have the 194 'flat end ' bulb for license bracket bulb..
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