Try doing it after just 100 miles...maybe the amount you are seeing is just the residual amount left over from normal use of the car or something. Our cars aren't high risk for problems without the can so maybe this is just the amount that shows up normally unless something goes wrong to cause a bunch of it.ive had mine on for roughly 10,000 miles now. its weird bc no matter if i empty it at 1,000 miles or 5,000 miles that is about the same amount that i drain. granted i think more condensation builds up in it in the winter months. either way i think it is doing its job.