This Link on the Lion engine failures is a good one. 
He has some auto manufacturer knowledge, and he is a Disco enthusiast. 
In summary, he says the failure issue is:
- related to poor quality control of the crank manufacture (described as "Monday morning crankshaft")
- there are not enough bearings
- the middle bearings are more narrow than the outer bearings
- there is less oil supply to the middle bearings
- the high oil filter means on start up, there is no oil pressure for some time, which is bad
- the reason for the design compromise was that the engine was designed to be East / West configuration, hence they shortened the crankshaft
- the worst thing one can do to the crankshaft is demands lots of torque at low revs, as the oil supply is more limited the lower the revs
- he is a fan of frequent oil changes 
I love these people by the way, so don't criticise the people (feel free to point out tech issues though!!)
Worst Diesel Engine on the Planet ?  Ford Lion V6 - Land Rover TDV6 SDV6 - YouTube
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