Sorry Mike to clarify, when you mention 60,-80000 miles and their done.Are you referring to pump life or N18 engine life?
theres so many things that effect timing chains on them,
1, from new car was leased and owner just added fuel as such and found they eat engine oil but not before running it so low as to start the wear off.
2. past owners dont change oil until 20k plus and use wrong oil.
3 past owners get in and just flor it from the off,
4 driving at high revs everywhere more revs more wear .
5 the biggest problem is its just made out of second rate parts, the chains are very small narrow and fairly long, bmw had a epic diesel 325tds engine and 2.5 petrol back with e46 bmw ages ago had a twin timing chains on them the changed to these single cheap chains to save some weight many felt in the trade at the time, seen those engines do 500.000 miles before on same chains, where these thin light ones dont see past 100k,,
just need to treat the timing chains as a service item has a life span, trouble is driving to far on a very stretched out of time engine will cause other problems, with 02 sensors and cat and even make ot run a lot hotter by running retarded all the time as it takes more uel to push a out of time engine added to the pre ignition and pinking caused. you can hide from this with any engine with a timing chain as most of the low emission designed cars have these days, as for scanning ot i use autocom cdp plus this gives live data and option to add actual and prescribed timing on them