Replacing the coolant (VW Passat B4)

During operation, the coolant does not require replacement. Only an annual check of the fluid level is necessary. If it is necessary to replace the coolant, perform the following operations. Remove the expansion tank cap. Disconnect the radiator supply hose from the thermostat housing and drain the fluid. Check the reliability of the fastening of the cooling system hose clamps. Pour coolant into the expansion tank to the MAX mark on the tank. Start the engine and let it run to remove air locks in the cooling system. Check the fluid level in the expansion tank and, if necessary, bring it up to normal.

(The original information is posted on the resource: VWMANUAL)