Indications of coolant "wear-out"

[k3eax]

I previously expressed reservations about Porsche's contention that its coolant need not be drained and replaced periodically. One reply seemed to indicate that the coolant was safe and non-harmful to the engine if the freeze protection level,as tested with a refractometer, proved adequate. This is not so!

Coolant used in an engine that consists of both ferrous and aluminum alloys contains silicates, a sacrificial additive that by its nature is "consumed". Such coolants should be testesd for ph and electrolytic conductivity. A quick test can be made with an accurate VOM. A voltage-drop of .3volts from the coolant to engine-ground would be an indication of coolant wear-out.

It seems to me that some are satisfied to over-look coolant condition until it does damage. "Life-time" coolant?

[AFJuvat]

Well, I'm the one that posted with the refractometer test. If you are going to disagree with me when I answer your question, at least have the decency to reply in the same thread I responded in.

That siad, I can most definately assure you that is IS so. I only maintain as of last count, about 30 Boxsters and 20 - 25 996\GT-2\Gt-3 that use the same coolant; so I think I might possibly have a vague idea as to what I am talking about.

Porsche coolant is phosphate and silicate free. This has been a standard Porsche specification since Porsche started producing water cooled cars back in 1976.

I do not recall the exact composition of the coolant off of the top of my head, I do know that it is a glycol based compound and is NOT compatable with other coolants (except some VW\Audi coolant of the same composition)

I have not seen any corrosion issues EXCEPT where the owner has used nothing but straight water to replenish his coolant.

As I also said in my response, that "lifetime" is a nice sales term, but in practical terms, is only applicable until some component requires replacement that would necessitate the draining and replacement of the coolant. Changing the reservoir or the waterpump will generally require the replacement of 1.5 - 2.5 gallons of coolant.

If you wish to change your coolant on a regular basis, please feel free to do so. You need some form of vacuum bleeding\filling system to really get the air pockets out of the system. Porsche coolant runs approximately $8.75 USD per quart. For optimum mixture, use 60% coolant, 40% distilled water.

Heed the warning about coolant incompatability. It is a terrible feeling to tell someone that the reason their car failed is because that prestone "dex-cool" approved coolant they used filled the coolant ports on the heads with a mass of jello that prevented the head from cooling, and that no, sorry, Porsche will not cover that under warranty.

AFJuvat