Are you having issues today? Also, some trucks are damn good trucks.. in this case 235K and it's still together is not a bad thing. Some don't make it 10K :D Either way, I do admire you trying to find someone that knows these through and through. You'll probably have a better experience that...
Welcome, plenty of problems sadly, but also some preventive maintenance that is known to prolong the life of the motor. I would advise reading some of the forums and learning more, we've got a lot of good and knowledgeable members here.
Welcome! I would start by taking some time and reading the forums.. You'll see terrible stories, but you'll also see good ones. It's no secret the EcoDiesel has it's issues, but the best you can do is learn to help extend it's life. Keep us updated and ask any questions you might have!
It'll warn you when it's low... if you have no check engine lights/etc drive it. But, if it's been more then 3 or 5K miles, I would add a 2.5 gallon jug to see if it responds.