Ptu (power transfer unit) keeps failing initially Lincoln stated it wasn't a serviceable part. No drain plug present. If left unchecked or serviced by sucking out the oil that gets burnt because of heat from the catalytic converter, the transmission and engine with only 1 quart of 70/140 fuild it could seize up and cause catastrophic failure the ptu could either bust open or lock up causing a severe accident as the ptu is just the the right of the gas peddle under your foot. Simce there isn't a fix form this part it must be warrantied for life fluid changed annually people need to know. They attempted a fix in 2018 with a water jacket attached to the side I have seen ptus with 25,000 miles on them already turning black. The oil is an amber see through color new. The ptu sits in a 5 sided box cooking away everytime you drive it there isn't even any passive airflow over it on 2016 and 2017 Mkz's and Ford Fusion and Ford Explorer all having all time AWD

- La Crosse, WI, USA