Go to the Lincoln dealer. Ask to see the manual. Look up "recreational towing." It will tell you the in's and out's of the vehicle the manual is for.
I tow a 2013 Lincoln MKX 4 down.
According to the 2013 towing guide the 2013 Lincoln MKS AWD and FWD are towable four down. Not to exceed 65 mph, weight of the FWD is 4204 lbs and the AWD is 4301 lbs.
There are other considerations that are outlined in the manual, such as idling prior to towing and interval for running engine for 5 minutes, etc.
Here is the link to the 2013 Lincoln MKS