A6 fluid flow direction
 

I've done a search and found conflicting answers and the service manual is vague, so I only want an answer from someone who has first hand experience and has seen the fluid direction.

Is the top port on the radiator transmission cooler the inlet or the return line?

I haven't seen first hand but all the research I did says top is return.

:toetap:

I've also read more people use the in at the bottom and out at the top direction when mounting coolers, but still about a third do it opposite.

Either way will provide more cooling, but one direction provides a more stable temperature than the other.

I was hoping for an absolute answer, so I didn't have to do personal experimentation.

Anyone?

I see many saying that is the correct flow, and havent seen anyone say the opposite until now. I was trying to confirm this for my cooler install also, but in the end I bypassed the rad completely so it really doesnt matter. Although the B&M cooler is marked "in and out" I spoke with B&M and they told me if its mounted with the fluid attachements up.. it doesnt matter at all. It would matter if mounted with the lines on the side only.

I pre-filled my cooler and the hoses before mounting to assure no air was trapped. I only have about 15 square inches still exposed to airflow and it's difficult to get the temps up to 170 when the ambiant is 50, unless I constantly hammer it. I'm about to seal off all the airflow until I know the actual fluid flow direction.