Totally overthinking it. Stick a pan under the radiator and drain the old fluid until it quits running. Close the draincock and refill to the top with the fluid you plan on using mixed properly (either get a 50/50 mix or mix your own). Make sure the overflow is topped up but not to the full point, just enough so it's not empty. Start the car and turn the heater without AC on. Once it reaches operating temperature, turn the car off, wait a couple of minutes take the cap off, top up and you're finished. You can also do this with the radiator cap off and just top off as you go but you can also get an overflow or a burped face of coolant if you're not careful so it's safer to do with the cap on.

This will change about 75% of the existing coolant. When you drain the radiator you'll still have some old coolant stuck in the engine block and heater core, but it's not important to get every last drop out of the car. All you're trying to do is remove any major acidity and put some fresh additives in the system as well as remove any loose debris that might be kicking around in the radiator.

 

Thanks for a well explained answer! I like easy!

According to Walmart's web site these should be compatible. Any concerns with these three?

 

jdmartin said it. I'll add, if you have run just water in it, you may have some corrosive issues due to galvanic response. If there is any color in it, flushing thoroughly with a cleaner is in order. Also, not all systems bleed the air out easily. Know your cooling system, especially if it is a hybrid with a storage tank. If your system is known to be hard to bleed, use a vacuum type bleeding system. Know if any bleeder valves are in the system at high points. Make sure your heater is on as you run the car. Check that you get heat out of it. If your water pump is external, check the drive belt for micro cracks.

 

Why not flush the system with a couple gallons of distilled water. Drain and fll with desired Coolant.

 

Well, if you have street pick up oil recycling, you would have some empty jugs for that then.

 

Use only Green coolant for Asian cars.

 

The color of coolant is not a reliable means of telling what the formula is. Nor is "for Asian Cars" even if it claims Kia, necessarily what KIA recommends. which is a green P-HOAT (Phosphated Hybrid Organic Acid Technology) coolant. There are counterfeits, so take a chance or buy from an actual KIA discount dealer. All coolants are pretty much safe for an aluminum engine now but the cooling properties may vary from the OEM design. If the temp gauge stays at the same place, probably ok. Some coolants have additives for water pump bearings. but like most modern cars, KIA used sealed bearing. Whjich brings you to the seals.....

 

Check your owner manual for Coolant Capacity. Use 50/50 pre-mix.

 

Answering my own question: the drain/refill (both the radiator and reservoir) came to about half a gallon.

That would mean you only drained about 1/3 of the old coolant. If you measured what you drained out. Sounds low.

If that's just what you added to bring it back to full, you probably have some air bubbles to work out.

When I flushed my coolant system on my 2014 1.6L I drained out about 3/4 of a gallon just from the radiator drain valve (excluding the reservoir).

Radiator + reservoir and only about a 1/2 gallon - something seems off.