how to change coolant of engine

Well, if your coolant is now full it will be difficult to get more in. If your coolant is over 2 years old it is shot.

If you are changing coolent to bring your antifreeze up to date , you need to drain as much as possible and refill with the correct amount of antifreeze and water.

This is a job I prefer to let a garage handle . Its usually not that expensive and there are issues of disposing of old antifreeze.

How are you going to add more antifreeze to an engine that is already full? The idea is to drain as much out as you can, even use a garden hose to flush out the block, and then refill with a fresh mix of 50/50 water and antifreeze. If you do this every couple years you'll probably dodge the annoying overheating/clogged heater cores/blown head gaskets/clogged radiator problems that the less informed have to contend with.

Chris

I normally disconnect the lower radiator hose, and then flush..That gets almost all the old stuff out, and you can start afresh.

IMHO it is wise to replace the hoses and the thermostat every few years, which makes the whole job a bit easier.

You really must have some poorly engineered and cheaply built cars if you need to change the coolant every couple of years and the thermostat every few. Four or five years on standard coolant and some eight years for OAT coolant is considered more than adequate. Thermostat, if it ever fails, which it probably won't. Taurus should find out which kind of coolant he needs to refill his system. OAT and ordinary ethylene glycol is not compatible. Even a small amount of coolant left in the system will react badly if the wrong type is used to refill. Also, it is possible that if the new coolant is refilled too quickly or if certain bleed points in the circuit are not attended to, there may be hot-spots, the heater might not work or the coolant level could suddenly fall with no warning. Read the drivers manual or consult someone who knows what is needed for your particular model of car.

Huw

Yeah, we do.. We have a couple of Buicks...OAT technology is not all it was cracked up to be. I said every few years, not every couple of years.

I've had bad luck adding a 50/50 mix because a lot of water wouldn't drain out of the system, so now I add the proper amount of 100% antifreeze and then top it off with water.

I don't replace theromostats unless they are no longer performing their job. I have over 100k on the original one in my kia and it still warms up to one line below the middle and never deviates from that position. However, I still say that changing the coolant every couple years is a good idea. Sure you can go longer, but then you wind up dealing with the problems I described. Corroded water pump rotors, failed water pump seals, plugged heater cores, plugged radiators, mysterious overheating issues, etc. Been there, done that. Got the greasy T-shirt to prove it.

As always, your mileage may vary....

Chris