When I bought my ecoBoost Mustang, I asked the salesman if it used 5w20 oil, as I had a bunch on hand for my 2011 Sonata turbo. He said yes, and I foolishly left it at that (he also said there was a compact spare, which there isn't).
I had the dealership do an oil change using my 5w20, and when I got home and checked under the hood I then (my bad, I know) that the filler cap (and the owners manual) specify 5w30.


My initial thought is that there is no harm done if I leave it until the next scheduled oil change to go back to 5w30.


Thoughts? Recommendations?


Thanks!

 

my 2014 calls for 5w20 and I'm using 5w30 full synthetic during the summer months and will switch back to 5w20 for the winter.


I would just drive the car and not beat on it.

 

Check your owners manual, it should list the range of oil weights for the environment and conditions which your car is driven.
The 5w20 should be be OK for your location.