How to change the coolant in my car

Are you replacing the same type of coolant that it had, and are you doing it before any corrosion or contamination occurred, replace any questionable hoses, fill radiator and reserve: although on some cars you should open some bleed screws to let out trapped air.

Are you replacing an unknown product with an OAT formulation? Then after draining (with heater valve in hot position), you should fill with water, run it until it is hot (without a cap), and drain, check hoses, then fill with your fresh coolant, bleed, etc.

If you are replacing plain water, or coolant that has been neglected, after draining (heater valve open) fill with a liquid commercial cooling system flush product, follow instructions, then rinse, check hoses, and fill, as before. I say liquid flush product as I’ve seen too many systems where the solid does not dissolve and ends up in the water pump.

Do not leave the cleaning product in for days, or you may be missing key parts if they dissolve. Note the missing thermostat seal from the above engine.

If you are diluting your own concentrate, use distilled water, not tap water, as the tap water container chlorine and minerals that will react with parts of the engine or radiator, or fall out of the mix and damage the water pump bearing or seal.