ESS Battery Pack Coolant Tip
The Roadster uses a very specific coolant type. Sierra propylene glycol coolant which has a fluorescent green color. Zerex G48 ethylene glycol coolant, more commonly used in the newer Tesla models, has a dark blue color and should not be used or blended with the existing coolant.
Propylene glycol is used because it is less toxic than ethylene glycol, but ethylene glycol has better thermal conductivity.