Make sure the engine is cool. Open the drain on the radiator and remove the radiator cap. Make sure you have something that will hold about two gallons like a bucket. Make sure you put the heat to full hot before starting. You will need the engine to be running to do this. When it's done draining, fill the system back up with either premixed antifreeze or a 50/50 mix of water and antifreeze. Start it up and let it run until it warms up. You will know this has happened when the fluid level drops because the thermostat has opened. Top off the radiator again. Make sure the reservoir is half full and check it for the next couple of days and top off as needed. That's pretty much it.

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2011 Ranger XLT, 4X4, 4 door Super Cab. 4.0L, 5 Speed M50D-R1HD, 3.73:1, 8.8" open differential, Jason Pace cap
2019 Ford Ranger STX FX4, Super Crew, 2.3L Ecoboost, 10 speed automatic, 3.73:1 with rear locker, Leer 100XR cap