Specifications - Note:  These specs only apply to the '03 VTX 1300S Retro
Cooling System
  Coolant capacity Radiator and engine 2.9 quarts
Reserve tank .25 gallons
Radiator cap relief pressure 16-20 PSI
Thermostat Begin to open 176-183° Fahrenheit
Fully open 203° Fahrenheit
Valve lift .3 inches minimum (8mm)
Recommended antifreeze Pro Honda HP Coolant or an equivalent high quality ethylene glycol antifreeze containing silicate-free corrosion inhibitors
* Try saying that 3 times real fast. :)
Standard coolant concentration 1:1 mixture with distilled water