Coolant capacities vary by automobile. Owners and maintenance personnel can locate the coolant capacity of a particular auto in the vehicle owner's manual or in manufacturer's service manuals. Amsoil, a motor oil manufacturer, offers an online database of vehicle specifications sorted by year, make and model on its website.
The volume of coolant in a particular auto depends on the size of the radiator and the overflow reservoir. In general, more powerful engines require larger radiators and correspondingly higher volumes of coolant. A four-cylinder engine may only require six quarts of coolant, where a full-size truck may require more than 20 quarts.