thanks for the input guys;
pulling the turbo outlet and checking the FICM are beyond my capacity for now, but won't be forever;

oil / filter are conventional oil/OEM/motorcraft;
oil change was less than 2,000 miles ago;
frequency (since i've had the vehicle/last spring) is at/less than 5,000 miles;
and i've been using lucas upper cylinder with every tank since last summer.