That really sucks man!
I am not sure about the fix, but I would think that there a fibres that must be floating around in the oil even when you remove the sock. A solid drain and flush are essential. Good luck.
M3 Vert TiAG/Blk - with every option
Mods: Clear Bra | Tints | Hardwired Passport SRX | Painted Bumper Reflectors | Keyhole Cover | 6000k Predator Chromiums | 6000k Philips Ultinons | 6000k HID Fogs | Philips Silvervision Corners | OEM LED Tails | Trunk Lip Spoiler | Eisenmann Race | CSL Diffuser | CD/DVD Swap | Small Antenna | Blackout Grille and Gills | Smoked Corners
Mods ready to install: Paddle Upgrade | ZCP Rotors | CF Interior Trim