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Discussion Starter #1
I bought a 94' STS a few months ago, and It's time for an oil change. I figured while I'm changing the oil, I'll also change the coolent before winter comes. I already know to use a coolent/distelled water mix, and to use the pellets and put them in the lower hose. :)

My question is, the car has 198,000+ miles on it; and I'm certain that the previous owner did not use distelled water in the coolent. (Somehow, I doubt that he even changed the fluid on a reguar basis). I'll bet that there is tap water in the fluid already. I read that flushing the system will do more harm than good. So, would you worry about the tap water that may already be in the system; and just drain and refill? Or is there something else that you would do?
 

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At this point just drain and refill with the good stuff. Tap water is not good for the system because it has minerals, iron content, dirty stuff that can cause corrosion. These effects are dilluted slighty with the antifreeze and coolant suppliment. By now there's not much you can do about the past. Just replace it with clean coolant/distilled and go from here.
 

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Discussion Starter #3
Thank you, that's what I thought.

I think that draining and refilling the system will use about 2 gallens. Can anyone confirm this?
 

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Sounds about right. Do you still have the Owner's Manual? It should list capacities in there somewhere. My not be perfectly accurate but should be close enough.
 

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Discussion Starter #5
I have the owner's manual, (I'll have to check it tonight to see what it says), but I'm sure it shows the maximum capacity. I don't think it would account for the coolent left in the engine, heater core, overflow tank, and various coolent lines. :)

I'll drain it from the plug in the radiator, and unhook the lower radiator hose to add the pellets. So I figure the radiator, and what little will come out the hose should be about 2 gallens.
 
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