If your Engine Oil is clean, I am pretty sure its your Water to Oil cooler. Somehow Engine Oil gets into the coolant system and not Vice-Verse, Probably due to Pressure differences. Bad news is that the Bentley Manuel Says Engine Removal in order to replace. Hope that's not the Case. Good luck...........................
Yep, this was me
SOLD - 03 RS6 Avus (905355)
Current - 03 Toyota Tacoma 4x4 double cab - the YETI, lifted, winched, snorkeled, lockered, skidded, geared