Thanks for the feedback, BimmerBreaker.

You're right that Hayaku's is an M62. The version of TIS I have doesn't have a separate entry for the N62 (I think it's a TIS version from 2005). Maybe they are the same. I'll search again and see if I can find anything. I didn't see anything in my Bentley manual that listed the N62 capacity.

Edit: It looks like capacity is 3.75 gallons and about 1.5 comes out of the radiator. Lots of horror stories about access to the plugs on the engine block here, though the e53 may be easier:

https://www.bimmerfest.com/threads/e...-v8-n62.657484

I realize it's not a full flush. Even optimistically assuming you get a full mix, I'd still be at around 1:16 old coolant mix : distilled water after four radiator flushes.

I'll take my chances with the brass screw. A lot of people are happy with them. I understand your point about not tightening it too much.