I have 1.8tsi with timing chain and aux belt.

Anybody have info on service interval or from experiance when it would be wise to replace aux belt?

After 60tkm and 4 years I don't see any sign of problem on it.

When did you change yours?

I changed the aux belt when changing the timing chain on my 1.2tsi Octavia mk2 at 10 years 150 k miles. The old original belt looked in perfect condition, not a single crack or any sign of bits missing or worn. It could have been left on no problem.

Good to hear that, for now I will check it from time to time for cracks.

On my old car belt was replaced due to cracks after only 2 years.