June 11, 2012. Neste Oil's Naantali refinery is back in normal operation following the completion of a scheduled major maintenance turnaround. The turnaround began in April and lasted a total of around six weeks, and will help ensure the refinery's good performance for the next four to six years. Neste Oil Corporation is a refining and marketing company concentrating on low-emission, high-quality traffic fuels. The company produces a comprehensive range of major petroleum products and is the world's leading supplier of renewable diesel.