My Porsche had alien blood
 

I know these cars are out of this world! But my box had green blood in its veins! No really, I drained the coolant for a w/p change and the impeller was perfect, thank god, but the coolant was prestone green!!

When I refilled, I just put distilled water. I plan to drive it a couple weeks and drain and refill with Porsche fluid/distilled.... I don't know what knucklehead cheap ass did this, but how damaging is this and should I take further action to clean out? It has been the fluid in this car for at least 20k and 3 years...

Any feedback gets beers on me next time in Charlotte!! Lol

The risk is whether the previous owner had fully flushed out the OEM coolant before re-filling with Prestone. If so, then there isn't any likely damage. But you will have to do a full flush (maybe two) to get all of the Prestone out before re-filling with the OEM coolant. This is because the Porsche OEM coolant isn't compatible with aftermarket coolants like Prestone.

Also, there is a chance that the green coolant was OEM. Porsche used green OEM coolant up until around 2005 and then switched over to the pink stuff. If the coolant in your car hadn't ever been changed (some owners believe that the coolant is lifetime and never has to be changed) there is a chance that it still had the green OEM coolant in it.

Bottom line: Flush out the green coolant completely and then re-fill with the pink OEM and you should be good to go with no worries.

As long as you weren't having over-heating problems, you could just keep using the green stuff (but if you do that use fresh stuff - you don't know how long it's been in there!)

If you plan to change over to the pink Porsche stuff you really need to make sure you flush out the green stuff. Make sure you turn the heat on to flush out the old coolant in the heater core. Mixing the green stuff with the pink stuff will produce a thick gel-like consistency wherever they come in contact that could impede coolant flow. Cracked heads are no joke!

Remember to cut the pink Porsche stuff 50% with distilled water. So 1 gallon of pink stuff = 2 gallons of ready to pour in coolant. The Porsche stuff seems like it's really expensive when compared to the aftermarket stuff, but Prestone is now sold precut 50/50. Cost wise they're not that different when you compare both cut 50/50.

If you are a PCA member, remember to ask your dealer for your 10% discount (most dealers do that).

Thanks guys!!! I am pretty sure this is original coolant now that you say all this. The car is exceptionally original and in very well maintained condition, which is why I was so confused to see it green. Either way, I will flush it thoroughly before putting in Porsche pink.

Just curious though- is the original Porsche green compatible with the newer Pink?

copied paste from Pedro's garage website:
"I chose not to go with the Porsche coolant.
If you do the same, be sure to get phosphate, silicate and nitrite free product such as Prestone."
so according to pedro, certain collants can be mixed with the OEM.
the complete article:
Flush Coolant System Porsche DIY

Yes, they are compatible.
My car had muddy coloured coolant, which my indie and I concluded was a mixture of the original green stuff and the newer pink product that happened when the dealer replaced the original expansion tank and just topped the system off.
When I replaced the water pump and thermostat a couple of years back, I replaced it all with fresh pink G13 Volkswagen coolant.