The specific type of coolant used in the Duke 390 may vary depending on the model year and region, as manufacturers sometimes make changes or offer different specifications in different markets. To obtain the most accurate and up-to-date information regarding the type of coolant used in the Duke 390, I recommend referring to the owner's manual or contacting the KTM customer support or authorized service center. They will be able to provide you with the precise coolant specifications for your motorcycle.