How old is too old, subjective question but I want opinions

I have a '93 with 152,000 miles on it. It is a diesel, so I'm not worried about that, but the small repairs have become more and more as of late. It was 11 years old when I bought it and it has spent another 11 years in my care. Just like you, I'm thinking about sending it on to next owner while everything is still working.