Thinking of buying a citroen synergie X reg. It is done 150,000 miles. The timing belt was replaced at 100,000 miles. When will it need changing again? Thanks!

Yes u need to replace the timing belt for sure!
You also need to replace the belt is regulator.
Even if the previous owner told u that it does not need replacement u should go to a garage, to check it just to be sure.
Generally the rule on most cars is to replace the timing belt around 38000 miles.
l replaced mine at 68000 miles but i'm a mechanic & l know what i'm doing.
If l was in ur place l would replace both the timing belt & the regulator. If the belt brakes on the road, the cost to repair the engine will be very high. Usually broken belts cause a lot of damage in engine.
Last but not least, u should consider that u will have a starting point by knowing that u replaced specific parts on ur car, in specific miles.
Before u buy the car go to a garage & check it if this is possible. If u decide to buy it, change anything that is necessary to be changed. It is for ur safety.

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