My father had a '74 240D, taken care of by a lifelong Mercedes mechanic.

When I met this man, I had my '84 240D .... he told me to use ATF in the tranny, and change it frequently. I am under the impression that he used the same oil in my father's car. I use Castrol Extended Mileage ATF, and change it every 3 oil changes, or 9-10,000 miles. It's not that hard to change.

That said, I'm looking at Red Line MTL as everyone says it makes the box shift better -- and should make it last longer, too. I'll still change it, perhaps every 15000.

One of the guys on here used Mobil 1 10W-30 in his tranny, but he was only able to put 533,000 miles on the car ...