Hi I was just wondering what people here think would be the best oil choice for my dads 300 SD mercedes diesel. the engine was rebuilt about a year ago. I dont know the miles on it. I do know it has been recieving 3k mile oil changes with whatever his mechanic has been putting into it. probably valvoline 20W50. He does about 12 mile trips to work 5 days a week and sometimes the car sees the highway but not that often. We live in Florida. I am asking because I plan on changing it for him soon instead of his mechanic. thanks for the info