Uhmmmm...i call bull**************** on the pink jelly remark. I put green stuff that was stated to be compatible with all coolants and it really was compatible with all coolants. no pink jelly.....
Not every coolant that is mixed with Porsche coolant will cause a problem, but some will. It is real, so why take the chance? Do a flush if you are not sure.
Here's a water pump that I pulled from a failed 2.7l engine:
The pink gel was also in the coolant passages of the engine and no doubt, the rest of the cooling system.
Here's a little reading on the subject if you are interested, click the quoted text for the link:
Pedro: