I got around to doing a suck and fill on my 2013 Silverado transmission. I have the Mityvac 7201 and was able to evacuate 4.5 quarts from the dipstick tube. The process was pretty easy. I plan on doing this every 15-20K miles. The thing is GM does not recommend servicing the transmission until 100K. I was planning on changing out the transmission filter at 60K, 100K just seems to long.