[JFP in PA]

The most probable answer is no one really knows for sure (your really can’t go on just the color). Porsche is famous for using unique fluids in their cars that they have formulated specifically for them. Problems with mixing incompatible coolants are well known and often come up on websites. In reality, if the system is completely drained and clean, you could probably use just about any coolant formulated for alloy engines; the only potential problem is when someone else touches the system. Many independents, as well as most dealers, automatically assume you have the OEM coolant in the car and will top off the system with the OEM coolant; which is fine as long as what is in the car in not already incompatible with the Porsche coolant. If it is, you have a mess on your hands. This is exactly why we only top off cars we have no history on with distilled water; we cannot afford to take the risk that the system will gel. As we have also found the OEM coolant to be an excellent product, we use it exclusively when we service the systems. It works well, lives a long time, and is really not all that expensive if you search out a reasonable source instead of the local dealer.

So if no one else touches the car but you, and the system is completely drained, you will probably be fine.