Engine flush and clean - worth it?

I am about to have an annual service on our Saab 43,000 miles always serviced, we have been offered an engine flush and fuel treatment along with a Saab 6 months warranty for an additional £150. (Annual Service £249 Platinum Service £399) Is it worth having the engine flushed and the fuel system cleaned?
Worth having the fuel system cleaned. I'm dubious about engine flushing oils in case either any residue of the flushing oil is left in the engine, or it dislodges lumps of hydrocarbon that block and oilway. The best way to flush an engine is the change the oil very frequently. Every 5,000 miles.
Answered by Honest John on

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