Ford Crown Vic with rear main seal leak

Thank You, good idea. Will try that. But do you know what this 'oil slinger' is?

I'm don't know what an oil slinger is but I once for a while had a Ford with a 351W, and it had spline grooves on each end of the crankshaft, that pumped the oil away from the seal back toward crankcase, pan. It leaked from both ends from day one new--- Ford put seals on it FOUR times, still leaked. Finally somebody figured out the it had the wrong crankshaft from the factory, the crank was for a 351 but meant for a marine application, and for whatever reason the marine engines turn backwards, the opposite direction, and the spline grooves were pushing the oil OUT. But I know, this does not answer you, the grooves are machined on the crank, and can't be removed. That's slinger is a new one on me.

The only oil slinger I know of is the one on the front of the motor, it is behind the timing gear on the crankshaft & "slings" oil up onto the gears & chain. There's no "slinger" on the rear of the crankshaft.