2009 Outback coolant change

[Hottontot175]

Hello all from a Newbie,
I have a 2009 Outback 4 cylinder, and would like to change the coolant. In addition to draining the radiator, should the cylinder block also be drained and where would I find the drains? Would I need to purge air from the system after adding the Subaru approved coolant? Would it be necessary to add the Subaru additive that is probably supposed to help the head gaskets seal?
Any suggestions would be appreciated.
This car has 60,000 miles on it and has not had the head gaskets replaced. I am hoping that by keeping the engine oil regularly changed and the coolant changed, the head gaskets might last longer.
Thank you,
Ken

 

[Ecmbuster]

This will help with an image but if removed, a new one should be purchased or re-sealed.
Another explanation with the included document as an example.
Subaru additive?
Use OEM Subaru coolant or equivalent. Test the pre-mix and use a hydrometer.
Yes there will be an airlock and that is why an "airlift" system is used:

radiator airlift - Google Search

Or multiple warmups and "burping" the coolant. Do not over heat.

Mixed coolant or pure:

Why You Should Never Use Distilled Water in Your Cooling System | Rislone

Many people have "heard" that distilled water is the best water to use in a cooling system. This is wrong! Let us tell you why.

rislone.com

You are your own warranty company.