Hello Knowledgeable Ones

Today I took my Vectra 1.8VVT (Z1.8XER engine) to the local Opel dealership in Cyprus for a service. They have told me that the cam belt needs to be replaced at the next service - 59,000 miles (now on 49,000 miles). I owned the car in England from new (Dec 2006) until November 2009, and has been in Cyprus ever since. Opel dealer also suggests oil changes (GM approved fully synthetic oil) every 5000 miles. My service book recommends oil changes every 20,000 miles / 1 year, and a cam belt change every 100,000 miles / 10 years. Will the warmer, dustier and drier climate really have an impact on the life of a cam belt? And if so, how much of an impact? Or is the Opel dealership just feeling the recession?

Thanks in advance for all of the knowledge!