Cornering light is an 1156, and it's the easiest bulb on the whole car. Socket is on top, twist it out, replace bulb, twist back in. Takes two minutes. I put LED's in mine for more light:
If a new bulb doesn't fix it, you could have a bad cornering lamp relay, and good luck finding one. Junkyard is your best bet (they're buried up under the dash). Same part for '79-91, all Panthers.
Use 5W-30 in winter, full synth for better flow at freezing temps. If you've got a leak, try adding a little brake fluid to the oil, it'll swell the seals maybe just enough.
1988 CVLX Formal Roof (Love Boat) POTM July 2019 & Aug 2020, 56K
E-code lights w/ relays, LEDs w/ switchbacks, 15x8 Ansen slots w/ 255/60 BFG's, Kenwood stereo, various hacks.
1988 CVLX (Destroyer) 1998-2001 driven to death 202K
1988 Squire (Chris Craft) 1996-1998 junkyard rescue driven to death 199K