Just to add my 2 cents. I had one of these on my 2002 F250. Yes, it does add 6 quarts. "hand tight on the lid"..... actually I found that I had to use a box end wrench around the handle to get enough leverage on it because of the huge O-ring in order to keep the lid from dripping oil. When I had it on my ford, I changed my crankcase oil every 5,000 miles and the paper towel filter every 10,000 miles which is way too soon. But, it was just piece of mind for me. And don't be surprised if your oil is just as dark as it was before the GCF. It made no noticeable difference in the color of the oil on my ford. Not sure how it will do on the cummins. I had mine installed on the outer frame rail under the driver's side door.