Dear Heat,

May this find you well. It is. Anti-freeze (mostly ethylene glycol) is attractive for - and lethal to - small animals (e.g., cats, dogs) on account of its sweet taste. I'd guess you'll want to capture the old coolant, even if you don't plan to re-use it. If you get a piece of clear plastic tubing, about 1/2" (inside diameter), you can put it over the end of the nipple, and still use a wrench to open the drain. The tubing will direct the coolant into a pan or jug.

I did this on a 93 945 normally-aspirated car, and it worked perfectly.

When you drain the coolant, let the engine reach operating temperature and turn the heater control to max, so that the thermostat and heater valve open, allowing all of the coolant - including that in the heater core - to be flushed-out.

When you re-fill, also make sure the heater valve is open. You may need to "burp" the car, to remove any air bubbles. This can be done by putting the car on an incline (a hill or ramps), first "nose-up" and then "nose-down".

Hope this helps.

Yours faithfully,

spook