95k miles on a 5.0L V8. Engine runs like a top with a steady diet of Motorcraft 5W-20 synthetic blend whenever the oil change reminder comes on. This issue started a week after the last oil change and at that time I did not use Motorcraft oil but rather Mobil 1 that was on sale. The FL500-S filter is the only filter I have ever used on it as well. Digging more into it, the alert will come on the dash when the engine is idling in gear. The slightest kick of the gas pedal will bring the pressure back to normal on the gauge cluster. This will not happen all the time but it seems to fix itself after an extended period. Any time the alert is on the dash the engine does not have any noticeable sounds or even a decline in performance. No ticking, knocking, sputtering or misfiring at all. So am I looking for a bad pressure switch or even a filter that's stuck in bypass? I am lost I will admit.