Gearbox oil cooler

[Eddiemex]

Fitted a Mocal laminar flow oil cooler and was wondering how much oil I should now run in the gearbox as there will be some extra capacity in the oil lines cooler and pump. I also thought I read somewhere that some of you run about 3 litres in your boxes. Anyone have an idea?
My Nob is a 3r by the way.