Caymandrew: "Description of 'using Transfer case properly.'
When the learned Rover engineers designed Rover's electronic traction control, they thought a locking center differential, CDL on LT230 was no longer needed, so they eliminated it, only to return it on the 2004 model to meet customer demand. Regarding proper use of CDL, the 2004 manual says to use CDL only temporarily, when needed, and unlock it soon afterward, to decrease the chances of driveline damage. THAT is proper use of CDL, and best policy. For normal off road driving conditions, low or high range, don't lock CDL, but lock it only for the most severe conditions, as they present themselves infrequently, and unlock it in between those infrequent times. To run around with CDL always locked for off road, is foolish and increasing chances of very expensive damage to Transfer case, to front differential, to front hubs, etc. Rovers without CDL, but with viscous coupling, such as classic Range Rover, are always susceptible to that damn viscous coupling freezing up without warning---it happened to me, and before I knew what was happening, (I was on pavement) the frozen vc, working same as CDL engaged on LT230, tore up all gears in my front differential and tore up the left front hub too. "Basically, lock CDL off road, or risk breaking it," is opposite of my understanding and thinking on this issue. Locking CDL off road is foolish and risky, and I won't be one doing it.
Jifir: "Lock CDL when you need it; unlock it when you dont'" is the best safest policy, in my view.
99Discovery: swore he would never get AWD viscous coupling T. case again. I did the same thing, and will never change that opinion in my lifetime. I don't have enough money or patience to get another one. He says it is tough to beat a geared T case, and I fully agree with him on that too. Yes, helical gears help make for more quiet operation, and for more ease in engagement too. He says that you would risk "wind up," damage to T. case (or other drive line components) if on surface (such as dry pavement) where wheels can't slip easily, with CDL locked---while slipping of tires on any surface, wih CDL not engaged is fine, though best to avoid even that as much as possible, unless you are young, crazy, not concerned about stress of parts, etc. I agree with that too.

 

I have an idea Ian Ashcroft has a good idea what he's talking about, but if you want to ignore his advice, have at it.

 

+1 - You can speculate all you want, Ian will still know more than you about the... well most all Rover driveline.