I have recently had to do a full engine overhaull on an 8v 2E engine from a passat
It was a taxi, then used for a 80 mile daily commute for years 259k miles. The car its self was very clean for the miles.
Reason for overhall was....
*Carry out full service & MOT investigate numerous faults as listed. <this is what customer complained about
Investigate rattle/tapping from engine when cold
oil leaking
This is what we found on the service.
Oil leak from camshaft area
Oil leak from crank seal
Oil leak from head gasket area
Engine knocking when cold adv possible piston slap
Oil pressure warning light on when revs drop below 800rpm
Noise from hydraulic lifters - Possible oil pressure
Coolant leak from radiator
Coolant leak from cylinder head flange
O/S/R Tail light bulb out
Had been serviced every year (turned out to be every 15-20k miles) And not been serviced for the past 4 years (40k miles

)
Anyway old boy told us to do the lot, so it had new piston rings, bottom end bearings, oil pump, water pump, cambelt, new intermediate shaft seals and bearings, head gasket, tappets, valve seals.. the whole lot.
Madness! Waste of money if you ask me but its nice to see it done, that engine will do another 200K miles + now.
To be honnest it didnt need a rebuild, the piston slap would have gone on forever, wasnt even smoking. Just had a small oil leak from the cylinder head. there was so much gunk in the engine from lack of oil changes though, it has lost oil pressure.
Wear on the bottom end was small, very little end float on the crank, within spec.
And this one wasnt well serviced. So of you keep up the oil changes and look after it... i reccon it will do a whole lot more miles.