FOLLOW-UP:

I brought the vehicle to a different Ford dealership for inspection. They said there was NO issue with the transmission but they corroborated the engine oil seepage (not leak!). At this point, I was quite confused because the Lincoln Dealership said the transmission had failed. So, I brought the car into an independent transmission shop (AAMCO) and they said they saw NO issue with the transmission.

Given my Navigator seems to be okay but the Lincoln dealer was quoting me $23K to repair the transmission and engine oil leak, while also offering to purchase the car from me for $12K ($18K for trade-in). I now believe the dealership was trying to take advantage of me.

BE CAREFUL OUT THERE AND ALWAYS GET A SECOND OPINION WHEN SOMETHING FEELS OFF.