OEM BMW 4-pin connectors are no longer available to purchase

The differential drain plug is a perfect fit and has the correct depth for proper detent spring compression

You can sand them

For programming software use BimmerTuningTools MS41 Quickflash and BTT OBD2 flashing cable

semi-permanent tire dressing on the market

Tesa Automotive Harness Tape Black PV6 19mm x 20 meters 6 Speed E36 M3 OEM BMW 4-pin connectors areOEM Tesa PVC Electrical Insulation Tape Common uses are non interior wire harnesses such as engine bay, wheels wells, etc. Tip: for a longer lasting adhesion at the beginning end, heat the last applied wrap winding and press the tape into itself.