oil/fuel system flush on 2008 Pontiac G6

At what mileage should you have the oil and fuel system flushed. I'm at 45500 and was told at the dealership that it was necessary to have this done and would cost 275.00. My gas mileage is great 34mpg highway and I get my oil changed at dealer regularly.

Asked by for the 2008 Pontiac G6
Car manufactures frown at engine oil flushes. Change your oil regularly (every 3000) and don't flush the engine oil as it not recommenced by GM. Fuel injection cleaning is optional if your gas mileage is good, car has no problem starting, idles well and you use good gas, there isn't a reason to flush the fuel system. I would add a bottle of fuel system to the tank occasionally and unless the fuel trim figures indicate the need for fuel injector cleaning or there is some other under lying problem there is no need for fuel injection system flush at this mileage.
Thank you so much for your advice.