[JFP in PA]

In order of criticality,

1. No particular brand of coolant is going to make your car run any cooler than any other brand, period. And don’t waste your time and money on aftermarket band-aid coolant additives; all they do is make your wallet easier to sit on.

2. The “story” behind staying with the Porsche coolant stems from the fact that it is not overly compatible with some other types or brands. When it the OEM coolant is mixed with a type it does not like, gelation occurs, leading to one Hell of a mess, and a significant expense to get it cleaned out and get the car usable again.

3. If the car was drained and thoroughly flushed of the OEM coolant, just about any aftermarket coolant compatible with Porsche engine alloys will work. But the trick is that you have to start with a totally clean system to be safe.

4. Any Porsche shop worth its schnitzel knows about the incompatibility issues and will only use the OEM coolant or distilled water (for top offs) to be safe. So if you bring them a Porsche with something else in it, they won’t know that and could cause an issue while performing normal maintenance on the car.

5. The OEM stuff is actually a very good coolant; we have seen cars 6-8 years old with the factory fill that still tested well for pH, freeze point, etc. So life expectancy should not be an issue, as long as the system is clean and the coolant is mixed with distilled water (prevents contamination and degradation of the coolant additives package).

6. All M96/97 engines run way too hot to begin with. If the radiators are clear of debris, they should be fine; but one of the biggest culprits is the OEM thermostat, which forces the car to run way too hot (do a search, this issue has been covered ad nauseum). Aftermarket 160F thermostats (same temp Porsche uses in their high HP cars like the GT2, GT3 and Turbo) will lower the general operating temps for both the coolant, and more critically, the oil (often by 20-25 degrees or more).

7. Another issue is the OEM water pumps; over time, the impeller often wears down, reducing coolant flow. Unfortunately, no one in the after market makes a replacement that is worth a damn, so you are stuck with the OEM unit. Jake espouses changing the pump at least every third year; and while that may be somewhat extreme, he has a point: They do not last forever.