Well, 300k is a lot of miles for any car so some blowby is inevitable. And if I'm an average 190d driver, that engine has been matted most of its life. Its a good engine though prone to head gasket leaks imo. It should run pretty smooth if its feeling good. Hard to beat the price if it runs.

I love my 190 but its a small car, so I wouldnt take the kids out to the grand canyon in it anytime soon.