First classic car

Get your factory service manual, buy classic car specific motor oil like Amsoil Z Rod oil and a premium oil filter like Wix or Amsoil (wix makes Amsoil filters to Amsoil specifications and it is a better filter). Follow oil manufacture recommendations on service intervals. Stuff is expensive but you won’t be disappointed. I have run Amsoil in my 3 previous new cars(different grade) and it works flawlessly. Amsoil stands behind their products and will repair oil related breakdowns if you follow their service recommendations.