You may be alright, then. Once one goes away from using the Porsche fluids that changes things...

On a long drive last weekend, the low coolant light flashed on my 99 Boxster. Got out and let the car cool. Sure enough, it was low. Still could see the level but it was below the min line. Ended up buying a 50/50 pre mix (water and coolant) from AutoZone as they were the closest. Added 1-2 quarts. Level hasn't gone down, but I didn't think I had a leak. Just probably lost some over the 8 years or so since I had some put in.

I didn't think it mattered much the type of coolant I put in, especially with such a small amount, but thought I would ask.

Greg
1999 Boxster

... in a healthy cooling system which is a sealed loop.
If the level dropped, the coolant went somewhere.
Most likely is the coolant cap that over the years may lose tension on its spring.
Check to make sure you have the latest coolant cap version available (it should end in 04).
Happy Boxstering
Pedro

Pedro Bonilla
1998 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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Racecar spelled backwards is Racecar

"Racing is life. Anything before or after is just waiting" ... Steve McQueen as Michael Delaney in "LeMans"

"If you wait, all that happens is that you get older"... Mario Andretti

"Being second is to be the first of the ones who lose" ... Ayrton Senna

You may want to check for moisture around the water pump. Since the Boxster is 15 years old, my first thought was a leak at the water pump, which could indicate that it's going to fail soon. Obviously, the coolant tank cap would be the cheapest and easiest fix. Coolant tanks are also known to crack.

Thanks, Pedro. The part number on my cap is 996.106.447.01. It seems to fit tight. Any way to check it? I don't see any leaks around there. There is just a coolant mark from where I spilled when filling it.

Probably the best thing to do is simply buy a new one, with the number ending in 04. That's what I did. I can't recall the price, but it didn't break the bank.

I'm sure it gives me some extra HP too
I'll look to get one.

properly topped up and the A/C off drive the around long enough to get the engine fully up to temperature. You want the engine and its oil and coolant to be at operating temperature and to have been there some minutes.

Back home then raise the RPMs to say 1500 and let the engine run this way until you hear or a helper hears the radiator fans come on.

Shut off the engine.

Have a tent of aluminum foil handy and cover the fluid access area. The idea is any vapor being forced out past the cap will encounter the cooler tent of foil and condense water on it.

After a few minutes you can carefully look at the underneath surface of the foil for any signs of water.

Or you can do as Roger987 advised and just replace the cap. This would be my advice too, BTW.

However, there may be some value to "testing" for a leak using the above technique. It really subjects the cooling system to high pressure when hot. Under these conditions of pressure and heat leaks are generally more active. Doing this test once ended up with the coolant tank finally letting go through a crack/split (that was the seam) at the bottom of the tank that once the tech removed the old tank was clear it had been leaking for a long time.

You might find that even with the new cap there's still a leak in the coolant tank and if so it is better to find this at your convenience not on the road late some night.

Great advice on the test, Marc!

I get condensation there now. I assume that I need a new cap too?

It's got be coming from the coolant cap or the top of the coolant tank. Replacing the cap is the cheapest, easiest fix. Try that and keep a close eye in that area to make sure it stays dry.

That's exactly what prompted me to replace mine. I saw the condensation there once, and once was enough - it shouldn't happen at all.

"A mile of highway will take you one mile. A mile of runway will take you anywhere."

seal that prompted me to replace the cap. Well, that, and the fact the system went low enough on coolant twice -- the 2nd time in around a month -- to have to add nearly a gallon of water to bring the level up to where it should be.

If you are seeing condensation without using a foil tent that's a sign there's a leak. Unless you have reason to suspect the tank I'd replace the cap first and keep an eye on the level and for any signs of condensation. If you continue to see condensation the your suspicion has to be towards the tank.

I never did it but you could I guess remove the plastic panel that floors the bottom of the basin which would give any rising water vapor a straighter path up. This plastic panel removal would be temporary until you were sure there was no condensation thus no leak, at least from the cap/tank area.

After 30 miles RT of city commute, I get a slight wetness or slime. No heavy buildup. I topped the system about 3 months ago (a little low only) and the level is still to the max. (After maybe 1500 miles). I will watch the condensation patterns and act then. Thanks.

monitoring. Thanks all! $27 delivered.

It is not recommended to mix coolants (anti-freezes).

I'm not sure how much of an incompatible anti-freeze is needed to trigger a bad reaction (gelling is what I read is the biggest concern).

Since what is done is done you might want to consider a coolant drain, perhaps given the possible mix of incompatible anti-freezes some kind of flush by filling the system with just water and running the engine until warm then letting it cool and draining this then refilling with a proper mix of the right anti-freeze and distilled water.

Sure it is some work and possibly an over reaction but at least you get the very important cooling system back to good known ground with a fresh mix of the right anti-freeze and distilled water. This is important to the water pump seals and the radiators, and heater core, and oil/water heat exchanger all of which are at risk of developing a leak (or worse) due to corrosion that the anti-freeze helps quell.

In the future, if the system is low on coolant adding distilled water is preferable if you can't add a mix of the right anti-freeze and distilled water.

(BTW, years ago I bought a gallon jug of Porsche anti-freeze. I still have it, unused. But I have over the years had the cooling system drained and refilled with fresh coolant, about every 4 to 5 years.)

The coolant I bought said it was universal and compatible with any color anti freeze. The other mitigating factor is that about 8 years ago I hit a curb and tore part of the system up front. The entire coolant system dumped. I had it repaired at an independent that I trust. I'm not 100% sure what type of coolant he used.

I will have to ponder this one.

obviously and maybe mixing fluids is not so risky given what you ended up with in there.

You may also want to check the carpet on the floor in the rear trunk .......on my 99 the coolant tank developed cracks in the bottom and it leaked hard to notice until the carpet discolored.