You can Run it 100 ml short. In the summer,it will expand anyway. You could always filter your old stuff and top,off

For those who have replaced their MTF, did you find that you needed a 3rd bottle to fully top off the 2.1L capacity? Or is the remaining .1L usually made up by fluid that doesn't fully drain? I have 2 bottles of Genuine Volvo 31280771 and am deciding whether to purchase a 3rd before I start the job...