... all Porsches.
The reason why you couldn't mix coolants in the past was that most engine blocks back in the day were made of iron.
In order to protect the iron they mixed in phosphates, silicates, etc.
Then, Porsche came out with aluminum blocks which does not like phosphate or silicate, so they had to develop their own coolant formulation.
If you mixed the coolant containing phosphate and silicate with the one that didn't have those additives, the mixture would gel and clog up the system.
Eventually other additives were used and more and more manufacturers turned to aluminum-block engines as well so now the norm is to have phosphate and silicate free coolants.
It is difficult to find a coolant with phosphate and or silicate now a days.
So now you can mix coolants: Porsche with Prestone or Zerex or Peak or ....
The color of the coolant is not an indicator of the additives.
Check out this article I wrote some time ago regarding coolants:
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pedrosgarage.com]
Happy Porscheing,
Pedro
Pedro Bonilla1998 Boxster 986 - 311,000+ miles:
[www.PedrosGarage.com]
PCA National Club Racing Scrutineer - PCA National HPDE Instructor - PCA Technical Committee (Boxster/Cayman)
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