5W20 is for sissies! J/K! That is for the Naturally Aspirated engines, not for the Ecoboost lineup.
For the Ecoboost engines, you need to put in 5W30. Manual says Motorcraft SynBlend is OK for the OCI (normal driving conditions), but I believe over time, it won't be enough. A full synth from Amsoil, Royal Purple, Pennzoil PUP or P+, or Quaker State UD, or Mobil 1 or Valvoline or Castrol Edge at the very least if sticking to 7500 OCI. 5,000 or less you can get away with SynBlend, again in normal driving conditions.
If you are an aggressive driver, stick with full synthetic, get used oil analysis done to see at what mileage you absolutely should change the oil (but don't go over 5K for the filter if FL500s). Highly recommend 5K or less even on full synthetic in these conditions (special operating conditions).
Got to remember, oil is what makes timing work, and if timing is off, just like anything else in life, it can screw you over.