The manual for my '83 240D calls for ATF. I think there were one or two years where Mercedes called for engine oil. I think that every year from the beginning of time except for those two years or so, Mercedes called for ATF. My ponton calls for ATF. I think that the later manual transmissions, i.e. like my '83, is the same transmission as the earlier ones that called for the engine oil. I don't know whether or not Mercedes changed their recommendation or not on the engine oil for those transmissions.

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Len
'59 220S Cabriolet-SOLD and living happily in Malta
'83 240D 351,500 miles original owner-SOLD
'88 560SL 41,000 miles - totaled and parted out
https://sites.google.com/site/mercedesstuff/home
'99 E300 turbo 227,500 miles
'03 SLK320 40,000 miles - gave to my daughter
'14 Smart electric coupe 28,500 miles
'14 Smart electric cabriolet 28,500 miles
'15 Smart electric coupe 28,000 miles