My vn has had oil changes every 5000km's and its on 206,000 and no rattle,no smoke,no losing oil or anything touch wood ..
only things that really go on looked after engines are waterpumps,inlet manifold gasket,timing cover gasket, harmonic balancers.
even if engines on 300,000kms+ can still be good ..
I can spend $2000 on reco engine with warranty fitted ... or I can spend money on getting gaskets and minor stuff fixed on an engine thats original from factory which is better than a reco engine and is still going strong after 20 years ..
if your engines got such low km;s then get the minor things fixed ...
I have seen friends run out of water and overfill oil on their engines cause they stupid and engines still go hard ...
dont think about a reco or rebuild until you blow a headgasket or bearing which will be hard to do with these engines if looked after ...
I was told head gaskets are very rare to go on vn-vp engines even when over heated ..