I wouldn't worry about telling the dealer anything!! As 1st rule of cars, Never, Ever trade a car in. You will lose a "minimum" of $3,000 and more like $5k to $7k. There are few exceptions unless the dealer is an idiot. I say this having been in car sales for over a decade and a New car sales manager at a Porsche, Bmw, Jeep ..... Dealership.
Here is the easiest way to sell a car.
1.) list it on these boards. Be honest about its history as we have access to all your previous posts. (It sounds like you are very honest anyways
2.) find the closest largest city and advertise it in their paper ($30-$50). Don't list your personal phone or address(buy a walmart prepaid phone for $20 if you have to). Meet them somewhere populated preferably near a cop shop and have a friend follow you if possible. The bank can help you with your paperwork if you don't own it out right. The paperwork is fairly easy as you need an odometer statement and title (in ohio).
I have sold at least 8 of my previous cars using method 2. I know it seems so easy to just drive into a dealership and do a trade, but You are throwing away money. At max $75 invested can return you easily $3k. I would really try to avoid selling a car to a friend as it will most likely come back to bite you in the ass. Trust me I learned that one the hard way.