[Mark_T]

It's only lifetime if you've owned the car from new and know without doubt that nothing but Porsche coolant and distilled water has been put in there and that it has not been compromised with polypropylene glycol, tap water, etc.

That, however, was not my question. I'm talking about checking antifreeze strength to make sure there is no danger of the coolant freezing during winter hibernation. There are a couple of ways to do this and I'm trying to poll the group to see who does what in which way and why. In other words, not interested in anyone's opinion about whether or not it should be tested, only in opinions on the method and equipment used by those who do test it.