Emergency coolant problem

I've got a 99.5 V6 A4 Quattro. 100k miles, timing chain and water pump changed at 80k. Oil recently changed by a new shop--good rep, but unknown competence to me.
I've got to drive 400 miles tommorow and just today discovered that the coolant level in the tank is quite low, perhaps 1.5 inches below the minimum mark with engine cold. Normal temp readings, no warnings during running.
I thought I had been smelling coolant on occasion but put it off stupidly till finally noticing the low level today. Must be a leak, but can I get away with topping off with Prestone Extended life or Havoline Dex-cool or whatever to get through this trip, then have my shop fully address the prob upon return? Should I dilute 50/50 with water for that small top off quantity? Dave
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Safe thing is to just add plain water, the VW/Audi antifreezes can gel if they are mixed with something incompatible.
Coolant loss might be a heater core failure.

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Understood on using distilled water, but I assume the best ting to use would be the G12 type coolant Audi specifies in the manual? I may be able to get some from a local shop.
I wonder how much adding say a quart of distilled water will increase the coolants freezing point? I doubt I'll encounter temps lower than 20 F on this trip? Dave
On Sun, 17 Dec 2006 20:54:15 -0800, "No Spam Please"

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Well, the best thing is probably to get your leak fixed. But you did say you were short on time.
You could buy a gallon of G12 and mix up 2 gallons of 50-50 mix with water and take those with you. G12 runs about $22/gallon around here, always in stock it seems.

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Safe thing is to just add plain water, the VW/Audi antifreezes can gel if they are mixed with something incompatible.
Coolant loss might be a heater core failure.

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and take some spare gallons of water with you on your 400 mile trip! The coolant/water should not freeze if the engine is keeping it hot! ;-)

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I do not smell coolant inside the car with heater on or off--only outside and around the engine compartment. Would you still suspect heater core failure?
On Sun, 17 Dec 2006 20:54:54 -0800, "No Spam Please"

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wrote:

In that case, perhaps not. Maybe a hose, leaking water pump, or leaking radiator.
Put a pressure tester on the radiator, and pump it up over night. Next AM check to see if you see seepage.
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Possibly. When I had my heater core fail, it actually leaked out around the firewall in the engine compartment and onto the ground.
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wrote:

Thanks to all who responded! I appreciate it guys. It turns out that there is a moderate leak (forget where). They patched me together, loaded me up with G12, and I made the journey without problem.
Thanks again. The input was extremely helpful. Regards, Dave
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