A mixture of 50% clean water and 50% straight antifreeze or you can buy coolant already mixed from your local auto parts store.
For 4.7L Magnum engine, it is the yellow plastic cap marked "engine coolant only" located on the driver's side of the black plastic reservoir at the very front of the engine compartment.
There's a plastic overflow tank in the engine compartment that you use to check the coolant level (add and full marks on the tank), and to add additional antifreeze if its low. It typically has a big black lid on the top and is marked showing that its coolant. You can open this with the engine hot to add coolant....do not remove the radiator cap while the engine is hot. Do not mistake the coolant tank with the windshield washer fluid tank. Both are clearly marked.
The coolant level is set by the level in the coolant reservoir. There is a line for the level if the engine is cold and a line for if the engine is up to temperature. You should fill it to the corresponding line.
There is a reservoir container marked "coolant" in the engine compartment. Add a mixture of 50% antifreeze and 50% water. (If you use "50/50" or "pre mixed" antifreeze, DO NOT ADD WATER). Let the engine get warm and fill to the full line.
For 4 cylinder engine. The oil fill cap is located on the right side (facing the car). It is clearly marked engine oil.
The coolant reservoir, it is usually a white or white and black plastic tank located on the passenger side of the engine compartment. In North America the lid will be marked caution never open hot. And Use only (a certain type) coolant.
It is usually marked, but halfway should be good.
At passenger side of engine, around coolant overflow bottle. Piece of tubing, with pressure port sticking out. Usually has cover, with L marked on it.
Most vehicles have a full line or add line marked on the coolant reservoir. Open reservoir only when vehicle is cold.
normal on the front face of the engine or the right hand side of the engine
If it is marked coolant the funny bottle gets the coolant.How it works:As the engine warms the coolant the pressure in the system increases as a normal result of warming. The pressure is released by the radiator cap by bleeding excess coolant into the bottle.As the engine cools the reverse happens but the valve works at much lower pressure (vacuum) going back into the system.It also works this way to keep it topped up with no air in the actual cooling system.You can see the valve that allows coolant back into the radiator in the centre of the cap id you take it off.
The bolt pattern is the same, but the 21R engine has 2 locator dowels, which must be accurately marked and drilled on the gearbox, if it has come from an 18R. The bolt pattern on the crankshaft end are not the same, so the flywheels are not interchangable.