My s320 consistently loses just shy of 1qt of coolant every 3-4wks. I can't seem to find leak. No smoke out tailpipe, no fault lights, temp guage reading never over 100, no rough idle, no contamination of oil, no water on ground but I have to top off 1qt every 3-4wks. Car runs fine with good gas mileage. Just did Etest everything was just fine.
Any ideas where it might be loosing the coolant.