I got an older w123 that came with a non oe 17 inch cheaper drain plug and o ring,i did my oil change and replaced the ring with the oe from a Mann filter kit,which i guess its too big and doesn't hold the oil.
If the oe plug is a 13mm and the car has a 17 mm should i get a smaller o ring?
help im stranded

Use a ring that fits the plug. They usually both come with the kit. If not reuse the old one if you are stuck and watch for leaks.

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Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician