I just bought an 81 300td turbo A/T. It was restored sometime 2004 and hardly moved after that.

I plan to change all the fluids and lubricants. All the benz guys I talk to tell me NOT to use synthetic oils. Something to do with the seals not being up to specs with synthetic oils. What gives? What oils and lubricants do you suggest for the engine, tranny, and diff?

I also noticed that the tranny's somewhat noisy. It was supposedly overhauled last year. The owner had the receipts for the parts he replaced. Nevertheless, here's a rattling sound when I run it. The noise becomes really loud when running it hard. I was doing 100kph earlier and it was too much to bear. Even the engine was too noisy.

Thanks in advance for your help.