1999 F250 diesel pickup. 1100 miles driven in the last year since being serviced. Do I need to change the oil?

Oil does lose it’s effectiveness properties with time as well as miles. I suggest to my clients to change it every 6 months even if they haven’t hit the mileage interval. Twice a year even if you drive 1,500 miles on each oil change. Customers who do this spend less on other issues than the ones who go a year or year and a half on an oil change. I can prove it with identical models and years.

Diesels have a lot of contamination in the oil (acids, soot etc). Diesel engines are really expensive and oil changes are not. Take care of it and it will take care of you.