I believe having your differential fluid changed was probably not necessary at this time, unless of course you've been beating the living crap out of it.
If you're concerned about deposits building up on the intake valves being this engine is DI you can do the cleaning yourself and save some time & money. Go to Walmart and get yourself a can of SeaFoam. They sell one which comes with a special shaped spray tube/anti-crush sleeve which will work with our Ecoboost's. Detailed instructions are on the can of course, but in a nutshell.... First you fully warm up the car and then shut it off. Then remove the rubber intake tube at the throttle body (* Pro tip
- Removal of intake airbox may facilitate this task), trim the special SeaFoam spray tube to the correct length (*Note
- when cutting the spray tube use a clean, sharp cutting tool. The inner diameter of the tube is pretty small to begin with and cutting it with something dull will crush it closed as it's cut. Ensure you haven't crimped the tube shut after making your cut), then reassemble with the SeaFoam spray tube/anti-crush sleeve in place. (*Pro tip
- Spray a little SeaFoam on the mounting area of the throttle body and a little inside the rubber intake tube. This will make reconnecting the two much easier). Now start up the car and connect the SeaFoam can to the spray tube and spray the entire can into the throttle body. You may need someone to give the car a bit of gas while you do this. My wife's Ecoboost didn't require it though. Once the can is empty you shut the engine off and let it sit for 15 minutes. Then take her out for a drive. Don't freak out if you see some white smoke from the exhaust. This is just the SeaFoam burning off.
Although this step-by-step guide was performed on a different brand/make car, the steps found in this online tutorial are basically the same for the Ecoboost.
I just performed this very same SeaFoam cleaning on my wife's Ecoboost last weekend. I plan on doing it every 25-30K miles.