The Bilstein Engine flush entails the connect of a closed circuit to the oil filter mounting place and the oil pan after the oil has been drained out of the car.
Then a heated solvent is pumped through the engine and allowed to travel wherever oil would be in you motor and clean the engine. It should remove carbon deposits and sludge. in theory it should allow the motor to look visually like new from the inside. The motor should run cooler and smoother.
After the predetermined cycle is run, the stuff is pumped into the flush machine and it is disconnected. Then the filter is replaced and the motor filled with oil.
So in short it is not just lil oil additive.
This product was featured a few years ago on MotorWeek on PBS.
Like I said before...I have seen the service for $80.
noel