Originally Posted by 
andeck
				
			 
			Thanks Shanegtr for your info from testing.
To the OP, I’ve had my d4 2011 for 4 or 5 months now and have just had my front diff replaced.
It was a decent whine from the front and similar metal contamination to yours. Near 200,000km, but bet fluids were never done! What a stupid idea when the qty is so small!!!
Anyway, I changed fluid three times and put in that nulon (g20?) additive which all did nothing.
Mechanic said after replacement that it was in actual fact a bearing, even though I was positive the noise was a gear noise. It came in with slight throttle load, and barely any noise when off throttle. Just thought I’d let you know that it was said to be a bearing, in case yours doesn’t improve.