Personally would change every 10k or year whichever is first. Timing belt on this engine due every 100k. I'd advise 60k as a maximum, always change with the water pump. Seen a few crank sprockets cause issues so get that checked/replaced at the same time too. Specialising in repairing & rebuilding Vauxhall 6 speed gearboxes.
Ive added a full step by step guide to my YouTube channel on how to replace the timing belt & water pump on a 2009 2.0 2.0 TDCI Timing belt & waterpump
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