Lionel 675 engine runs slow

[ADCX Rob]

Unless you are using a modern synthetic grease like Lucas Red "N" Tacky #2, then almost anything is better than "Lionel Lubricant" as it was sold. Motor oil is fine, Mobil 1 or Amsoil(or other synthetic) being a first choice, and then "Dino" oil as a better-than-adequate lube for Lionel engines.