i have a 2014 mazda cx9, should i change oil before trip or after have about 3700 miles on this oil , which is motorcraft 5w-20. Trip is about 1400 miles.
Assuming your engine's in good shape, 3700 miles is nothing on Motorcraft oil and the additional 1400 highway miles are easily within a reasonable OCI. Run it and change at 7500 or Mazda's recommended interval.