Larry928GTS

Does anyone know what the thread size is of the oil pan drain plug?

I noticed that there are two different part numbers shown for the oil pan. One part number is for the '78-'88 cars, and the other part number is for the '89-'95 cars. What's the difference between the two different pans? Drain plug? Oil level sender? Some internal difference? Something else?

Vilhuer

One difference is oil feed hole used in 16V cars. It was made to early MY 32V engines as well but discontinued around '88-89. Raw casting remained same but hole were simply not made anymore and there were no need for separate cover plate used in early 32V engines.

hacker-pschorr

IIRC 78-79 and some 81 cars have a larger drain plug (my 81 had the larger plug).

The smaller hole pans have a heli-coil for threads, the early cars are bare aluminum - you can guess how well that works.

ZEUS+

For drain plug:
part # 911.107.197.01 19mm one source says 80-95, another 81-95
part # 911.107.176.03 21mm one source says 78-80, another 78-81

blown 87

BMW and a few others still use that method.
Quick lube places do not change the crush washers and they soon strip out using the old washers.