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It is water.
It's normal for a car that sits for a long time or only gets driven short distances, especially when the outside air is humid. This would be just moisture condensation. You get rid of it by driving longer distances to let the engine fully warm up and stay hot, for the moisture to evaporate. Like an hour on the freeway. Time for a road trip! An oil change wouldn't hurt either, you can start with that to get some of the moisture out quicker.
It *can* be coolant too, which would indicate a head gasket leak or in case of a watercooled turbocharger, the seals in the turbo. Since your turbo is so new, I don't think the gaskets are suspect.
A shop can pressurize your cylinders (Leakdown test) one at a time and then look at the coolant through the filler hole, a leaking head gasket would eventually cause bubbles in the coolant. (and pressure loss during a leakdown test).
You can also buy your own leakdown tester at any auto parts store, I can't remember prices right now but it's not bad. You also need an air compressor to use it.
So, change the oil, and make a habit of driving the car on a longer trip like an hour or more, one day a week. See if the milky, mayonnaise looking residue goes and stays away.
I did just go on a one hour run, but 3 months prior to that, the car was used for a 3 mile commute to work and back. I usually let it warm up 5 - 10 minutes. And the last oil change was 4000 miles ago with mobil 1 extended care. Could this milky white mayonaisse greasy stuff be just a little harmless condensation?
My buyers are going to call a saab mechanic tonight? Do you think most mechanics will say that this is a definate sign of a need for a head gasket? I just don't know how to reassure my buyers that this is not a big problem. Any suggestions?
A mechanic that has a lot to gain in this, like someone who wants the head gasket job for himself, may be tempted to jump into that conclusion.
A 3 mile commute is a VERY typical cause of moisture condensation. That alone tells me it's most likely just normal condensation, given our current season too... wet and cold. When the engine cools down after a drive, it attracts moisture from teh aurrounding air. Water also gets in the engine through normal operation in intake air.. and finally, water is one byproduct of combustion as well. The coolant may get fully warmed up, but the oil takes longer to heat up and it needs to STAY hot for a good while for the moisture to slowly evaporate. Then the moisture vapors need to be vented OUT of the engine, which only happens when the engine is running. (Called positive crankcase ventilation, PCV). There is a small plastic valve on the valve cover, with a hose leading to the intake side somewhere, that is supposed to suck air out of the crankcase (Through the cylinder head and valve area). If thisPCV valve gets clogged or the hose disconnected or clogged, the ventilation doesn't work and the water vapors don't have a way out. As the engine cools down, the vapors condense back to water again.