T5 cams

[Disgruntled]

My '05 Multivan started puffing into the airbox ( 170,000km). One inlet valve stuck open, and one lobe worn completely off camshaft.
Sourced 2nd hand engine (130,000km)from Sydney, lifted the rocker cover and found the same problem.
Always used the VW spec ( dear) oil, at recommended interval.
Change your oil more often than recommended 15,000km interval, and I suggest using some sort of engine flush to clean the deposits out of the oil galleries to maintain oil flow to all the clattering internals.
Keep an eye on water pump leakage( into the block!) which quickly gums up the oil and exacerbates the problem.

[Umai Naa!!]

Cam wear was pretty common around that time for a few different VW engines.

There should be a revised camshaft, made from more appropriate materials, available for them now.

[Transporter]

Yeah, and maybe more common in US and Australia, because many choose to ignore the manufacturer's recommendation and the dealerships were allowed (at least at the beginning) to use the oil of their choice from the local market (go figure).

These engines in T5s were on an oil change interval of 50,000km or 24 months, so the original camshafts couldn't be that bad. I know from my source in Europe that there were many of these vans that done 500,000km with oil changes 50,000km apart. It still wasn't enough to convince me to change my oil at 15,000km.
....and what would I know, later the VW have revised the servicing interval to 15,000km/12months.

I've seen some R5 engines where the owners used Penrite HPRDiesel5 in them, failing at around 80,000km. So, it takes some time for the engine damage to show.

I've done 130,000km on my 4motion, the engine runs a whisper quiet. I change my oil every 6 months usually 6,000-7,000km intervals. Agree on engine flush, also used LiquiMoly Engine Protect, now LM MOS2 (after 100,000km) at every oil change. The fuel economy under 10L/100km hills and city driving only with many being a short trips.

[Disgruntled]

Dangle a magnet in the oil drained from your engine and check for debris. it might be a good early indicator.

[Transporter]

Even better... use magnetic drain plug.

....and always inspect the used oil filter for contamination.