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Locate the drain valve, also known as a petcock valve, in the lower radiator tank. Place the drain pan under the petcock valve and open the valve, allowing the fluid to drain into the pan. Remove the radiator cap.

Locate the thermostat housing by following the upper radiator hose from the radiator to the engine. The thermostat housing is at the end of the upper radiator hose.

Remove the two or three bolts that secure the thermostat housing to the engine by turning them counterclockwise with the socket and ratchet. You may need the universal swivel to access these bolts.

Grasp the thermostat housing where it connects to the upper radiator hose and pull sharply up at an angle to remove the housing. Make note of the orientation of the thermostat.

Remove the old thermostat. Use the gasket scraper to thoroughly clean off remains of the old gasket from both mating surfaces.

Install the new thermostat with the same orientation as the one you just removed.

Apply a thin coating of the RTV silicone to both housing mating surfaces and place the gasket against the housing.

Line up the bolt holes in the housing with those in the engine and replace the thermostat housing.

Install the retaining bolts by inserting them into the bolt holes and turning them clockwise until finger tight.

Torque the bolts to between 30 and 40 foot-pounds.

Close the petcock valve and pull the drain pan out.

Refill the radiator with the new coolant. Start the engine and allow it to reach normal operating temperature. Top off the coolant level as needed. Replace the radiator cap. Top off the overflow bottle as needed.

Pour the used coolant into a suitable container and take it to a local repair shop or parts store for recycling or proper disposal.

Open the radiator drain plug by inserting a -inch ratchet drive into the drain plug, then drain 2 gallons of radiator fluid into a drain pan. The plug loosens by turning the ratchet counterclockwise. Close the drain plug once you drain the fluid. This drops the fluid in the radiator below the height of the thermostat. This prevents fluid from draining from the radiator hose as you replace the fluid.

Locate the area on the top of the engine where the upper radiator hose connects. The hose connects to the thermostat housing. Remove the hose by loosening the band clamp with a screwdriver, then pull the hose off the thermostat cover.

Remove the two bolts that secure the thermostat housing to the Ford Focus with a 9/16-inch socket. Lift up on the housing to remove it from the engine.

Pull the old thermostat out of the intake manifold and then place the new one into the intake. The design of the thermostat allows it to fit into the intake in one manner.

Lift the old gasket off of the intake manifold and wipe the surface clean with a shop towel. Place the new thermostat gasket onto the intake.

Wipe the bottom of the thermostat housing clean with a shop towel and place it on top of the gasket. Tighten the thermostat housing in place with the old bolts.

Slide the hose onto the thermostat housing and secure it by tightening the band clamp with a screwdriver.

Open the radiator cap on the top of the radiator and drain the 2 gallons of fluid back into the Focus. Close the cap once you are finished.