I'd maybe try some 15W-40 or some 20W-50 and see what happens. If it's already that tired, probably ain't much gonna bring it back. Some folks around...
If you mean adding much extra, not really at this point. All four relay slots are used. Horn, Headlights (Hi/Lo relays), and E-Fan are in there. Most...
My Cars:
-1964 Comet 202 (116K Miles) - Awaiting Resurrection
-1987 Grand Marquis Colony Park LS (325K Miles) - April 2017 + September 2019 POTM Winner
-1997 Grand Marquis LS (222K Miles) - The Daily Workhorse & March 2015 + January 2019 POTM Winner