When I do the drain and fills on my 02 GS3 its usually a little more than 2quarts.. about 2.4quarts... I usually just measure whats drained out in a container with lines that I got from the dollar store... and yes its accurate, I checked it first with pre-measured water to make sure the lines weren't off. I wouldn't expect much more to come out of the a GS430 but I would just measure to be safe.