Toyota Avensis Tourer maintenance advice needed

I own a Toyota Avensis Tourer (2009) diesel with 80,000 miles on clock. Can you please advise me whether I should have the timing chain changed along with the oil, water pump and tensioners? The economy has dropped by 10mpg in recent weeks. Would you recommend an engine cleaning service like Terraclean or any other lubes for improving mpg?
As long as the oil has been changed regularly then the timing chain should not need to be changed. The mpg issue may be due to a dirty fuel system. I suggest you start using Shell V-Power Nitro Plus diesel and never use anything else. The improved mpg should pay for the higher cost.

Use only the oil specified in the manual by Toyota. If the engine is coked up then an engine cleaning service like Terraclean or EDT:
Answered by Honest John on

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