1989 Toyota Supra knocking

Engine problem
1989 Toyota Supra V6 Two Wheel Drive Automatic 170000 miles

1989 TOYOTA SUPRA 3.0L TURBO INLINE-6 WHATS THE CAUSE OF PUDDLES OF OIL ON THE VALVE COVER NEXT TOTHE SPARK PLUGS & RECENTLY STARTED MACKING A KNOCKING SOUND, WHEN I GOT I HAD TO ADD 3 QUARTS OF ENGINE OIL IT WAS VERY LOW IS THAT CAUSE OR DOES IT HAVE TO DO WITH AIR & FUEL MIXTURE IS IT RUNNING TO LEAN? PLEACE HELP OUT GUYS THANKS.