Certain cars like Hondas and Subarus like a very specific type of coolant. In fact, the generic FLAPS* coolant, when used on Hondas/Acuras, is referred to "Hondacide" because it does a job on your seals and waterpump.
My Honda owner's manuals and shop manuals say to use a high quality ethylene glycol coolant that doesn't have silicate corrosion inhibitors, and the premixed Prestone product I use fits this description according to the label. I've been using this stuff in my Civic for years and recently started using it in my Honda Shadow motorcycle, and I've had no problems. It's the same color and type as the expensive Honda coolant I can buy at the dealerships.
@texases and MB,
Although the distilled water will be the cheaper route, I have a bad feeling about Robert Gift’s DIY skills. Maybe I am wrong about this, but given what we know about the OP, I just don’t think this guy should go out of his way to save a couple (okay, maybe a several) bucks and over-complicate the project.
I like to keep things like this simple - less to worry about, especially for someone who drives in extreme climates.
As an idealist and perfectionist, I dislike compromise, especially if result is unknown.
With my background in chemical engineering, I am worst case scenario-ing that some deposit may begin a build up and damage seals.
As much as I am always gentle on the vehicle, it does experience some stresses in emergencies, like 95 mph for an hour, (still, the hospital calls and asks: “Where are you?”) so I try to be as good to the vehicle as possible.
But I hate paying premium prices if I can get the same generic for le$$.
A parts house owner several years ago sold distilled water by the gallon and a shop owner dropped in with several gallon jugs to be filled while he waited. Being bored, the shop owner walked behind the counter and into the shop area and found the jugs being filled from the tap at the wash basin. A few blows were exchanged but no one required medical attention. In the next few weeks all the parts houses quit selling distilled water and assured the shop owners that tap water was OK for batteries, radiators, etc.
Maybe, but you should check the pH first. When I owned a back yard pool, the pH would drop as time went on. It seems to me that the rain washed the acids out of the air.
Clear rainwater??
Sure - Maybe you can even use the sweat of 30 year old supermodel virgins but collecting it may seem a bit difficult and hardly worth the effort.
Just play it safe - get some distilled water for a buck or two and call it a day.
"You can use clean rainwater"
You can’t do that here in east central Indiana. We have had the least amount of rain in June that I can remember. I installed a rain barrel to catch the water from my downspout to use in watering my garden. I installed it just after Memorial day. It doesn’t have a drop of water in it. The water from our municpal water system contains quite a bit of calcium, even after it goes through a water softener. I have had to purchase distilled water for the humidifier on the piano at my church. Even with the softened water out there, the pads get limed up. I don’t think I would use this water in my car’s cooling system, except to top off the reservoir. I know that the coolant contains rust inhibitors, but two gallons of distilled water at 85 cents a gallon is pretty cheap insurance.
I’ve heard it said – by people who aren’t car experts but have scientific training – that distilled water is bad for the car’s cooling sytem. It lacks dissolved minerals, and water has a sort of “need” for dissolved minerals, so this makes distilled water more corrosive than tap water (which has some dissolved minerals in it already) as the distilled water tries to dissolve the engine and head. Well, I’m not saying it like the scientists said, but that’s the gist of it. They told me to use clean tap water instead for this reason, along with the coolant of course, in 50/50 %. I heard this years ago. Just curious if the opinion has changed over time.
I would think that the rust inhibitors in today’s coolant should neutralize the electrolysis effect of any metals in the engine that would tend to make the distilled water corrosive. I suppose the thinking is that the dissolved minerals in tap water would tend to make it more alkaline and counteract whatever dissolves to make the distilled water corrosive. However, I’m not a chemist (when I took chemistry classes, the only known elements were earth, air, fire and water).
We had a loooooooooooong discussion about ‘hungry water’ several months back. The moment the water goes in the cooling system with antifreeze chock full of chemicals and plenty of metal/contaminants, it’s far from ‘hungry’. Not worth worrying 1 second about.
@GeorgeSanJose–your information may be correct. The pH of pure water is 7. If the water is acidic, the pH is less than 7 and if the pH is greater than 7, the water is alkaline. I remember years ago in my junior high agriculture classes testing soil. If the soil was too acidic, it needed to be treated with lime to make it less acidic. The dissolved mineral in water is usually calcium which is lime. The tap water, then, would be less acidic or corrosive.
Not saying acid rain has no effect but pool water ph also naturally drops due to effects of chlorination. The addition of stabilizers helps counter that but occasional use of ph up is not uncommon even during periods of no rain around here.
The quality of “tap water” varies widely. Seen situations like TSMB mentioned to untreated super soft well water. So I would never put all tap water in the same bucket so to speak.
Looking to save $3.00 every couple years smacks of pennywise and pound foolish to me. I like to save a buck as much as anyone but some things just aren’t worth fooling around…