hello all

I am helping a friend look for a used car for under $4K, and i have been praising to him about diesel benzs. I am a tech. at a ford dealer, and know my way around cars very well even though i'm still a student. Anyways, I would like to know which diesel benz would be ideal for my friend. Sad to say my friend is very lazy when it comes to maintaining cars so it would probably have to be one that wouldn't require valve adjustments every 15k like i've heard most of them do. He just wants something cheap, that will last, and is under $4K. Give me all the info you've got on stuff that goes wrong with these cars, how many miles is too much, etc....

Thanks,
Mac