I drained my cooling system tonight so that I can refill my system tomorrow with the correct antifreeze before freezing temps hit here in Indiana and iv got a question. Can I run tap water with the prestone extended life I'm going to be putting in. My water goes through a water softener before it hits our taps and iv never seen any buildup from hard water so that's why I'm asking. I know that normally, tap water in the cooling system is a big no no and your suppose to get distilled water but if I can get away with my tap I'll just use it.

 

you don't want anything in the water or it will leave deposits as well as making your coolant conductive which will lead to other problems. short term it's probably fine but just get a couple gallons of distilled and do it right the first time.

 

I agree short term is probably ok. What do you mean by make the coolant conductive? I was under the impression that nearly every liquid was conductive. I have heard copper head gaskets you have to add a tablet to the coolant, are referring to something like that?

 

Water isn't conductive in its purist form, the minerals and other things it picks up along the way are what makes the water conductive. You will get what is called electrolysis which will allow deposits to start building inside the system.

 

To help combat this, go to your parts store and get a " sacraficial anode "
Made of zinc and // or magnesium. If you have anything aluminum that comes in contact with the coolant, it would be a good idea.
Just my .02

 

Every engine built early 1980's up will usually have something aluminum touching coolant and I rarely hear of using tablets unless its with copper head gaskets, so, why use a tablet?

 

I never thought about it that way.
My 1st rebuild in '80 had an alumimum intake. In '91 I blew it.
I used tap water to mix with the coolant. There was pitting in some spots & gray looking ashy build up in others.
'99 my bigblock had aluminum intake. I used distilled water & the anode. 2005 sold the body kept the motor. The intake was clean-- no pitz or ash looking stuff.
You have a good point! It very well could be that the distilled water prevented the condition. The anode looked new still.

 

as I have understood it, the types of engine coolant used have changed to adapt to the aluminum corroding, such as General Motors Dex Cool.