When models 2017 and 2018 came out the cars warned to do an oil change too frequently, it mentioned oil dilution. The car has no way of knowing this, it doesn't analyse the oil. A number of forum members (here and other forums) have tested their oils yet found the actual dilution to be minimal. LR referred to it as an early service warning issue and fixed it with software updates. My 2018 had its oil changed under warranty at 3 and 6 months, software updated at 6 months then at the annual service again. The second year I had no issues with additional oil changes at all, oil was changed after 12 months at the normal service.

There's many on this forum stating there is an oil dilution issue, but if you asked the actual owners I'd be surprised if any suffered actual oil dilution to the point where it was warranted the oil be changed when the car gave these "early oil change/service" warnings. I've owned a 2007 Nissan Pathfinder where you could see the oil level on the dipstick going up - I do believe that suffered from oil dilution way more than my D5 does.

I can't comment on the crank or inlet manifolds, I haven't read of issues here and on disco5.co.uk there is one report of something going bang but no explanation as to what the issue was.

Ron