According to the 2006 Mercury Mountaineer Owner Guide :
The vehicle came from the factory with a 50 /50 mix of distilled water and :
( Motorcraft Premium Gold Engine Coolant , yellow colored , meeting Ford
specification WSS-M97B51-A1 )
Coolant for a 2006 VW Bettle is put into the coolant overflow tank. As it is needed, the radiator will automatically pull in additional coolant.
Take radiator cap off, fill radiator with coolant, put cap back on!
There is no drain plug, remove the lower radiator hose to drain coolant.
The thread on cap on your engine coolant reservoir is the pressure cap / radiator cap
The radiator plug for a 2006 Dodge Ram 1500 is located on the bottom of the radiator on the right side. It is used to drain the coolant during flushes and fluid changes.
Stand the bike upright and examine the coolant gauge.
It is just below the housing that the radiator cap goes on.
If you are looking for the sensor that reads the coolant temperature, which the ecm uses to decide when to run the radiator fans. It is located near where the upper radiator hose hooks to the engine.
If you change the coolant as recommended in your owner's manual and use the proper coolant mixed 50/50 with distilled water the radiator can last the life of the car. Neglect this service and it may only last 10 years or less.
It is just below and behind on the area where the upper radiator hose attaches to the engine.
Low coolant, bad thermostat, bad fan or fan clutch, damaged radiator, debris filled radiator. Check your lines. Worst case scenario, blown head gasket.
The coolant temperature sensor is the two wire sensor near to where the upper radiator hose attaches to the engine. The outside/ambient temperature sensor is behind the front bumper, in front of the radiator.