When I purchased the car, the engine had 12,000 miles on it already. But I have all the service records and the oil was changed during the first 600 miles.

Shame on me. A friend offered me some filtered WVO and I mixed it with my diesel fuel for about 6 months in a 50/50 mix. Starting to think that was a BIG mistake. Whatever I saved in fuel, it will probably cost me double that for new injectors.