Coolant low - Can I top off with distilled water?

[JTNY]

I have the blue colored "type-2" fluid in my reservoir on a AP1 . I'm currently at the "Low " level and would like to top it off to at least mid level.

Is it advisable to add distilled water? Or, should I buy a gallon of Honda coolant and top it off?

[bimdub]

only coolant should go in the recovery bottle.....IIRC....

[repiv]

How cold is it right now where you park your car? If you put just distilled water into the reservoir, it might not mix with enough anti-freeze before it freezes up. Before you decide that you need to add anything, try to determine the real condition of the cooling system. If the system is full and the engine is stone cold, then having the level at the "min" (or low) line is just fine and normal.
To determine what you need to do, open up the rad cap (when engine is stone cold) and take a look. Is the fluid right up to the radiator neck? If it is, then it's full and what you see in the reservoir is fine. You only need enough in there to cover the opening at the bottom.
The difference between the low and "full" mark on the reservoir is very small, perhaps only 1/2 qt. or so. It's really not significant so long as the system under the rad cap is right to the top. If you must add any and all you have is distilled water and you don't want to do the rad cap check, then I suggest you do so and then immediately start the engine and go for a drive or at least idle it till the rad fan comes on. This will push expansion fluid into the reservoir, mix with it and lessen the chance of freezing. Seeing the level then rise as it gets hot will also tell you that the system was indeed full. When the engine cools down again, it will draw some of the fluid back in and continuing the mixing inside. A little pure distilled water won't dilute things out to the point that you will lose the proper concentration.
PS. Type II Honda coolant can be purchased in less than 1 gallon jugs. I recall buying it in smaller amounts, but maybe it's just here in Canada.

[JTNY]

It's presently in storage in my garage and so far its prob avg. bet 20-40 degrees in NYC. You might be right about starting it up and seeing what the level is. I guess I'll add that to my pre-startup procedure when it is taken out in April. I was just checking up on everything when I noticed the coolant to be below the "Low" line.

I'll also check with Honda about the smaller sized coolant containers.


thanks again!

How cold is it right now where you park your car? If you put just distilled water into the reservoir, it might not mix with enough anti-freeze before it freezes up. Before you decide that you need to add anything, try to determine the real condition of the cooling system. If the system is full and the engine is stone cold, then having the level at the "min" (or low) line is just fine and normal.
To determine what you need to do, open up the rad cap (when engine is stone cold) and take a look. Is the fluid right up to the radiator neck? If it is, then it's full and what you see in the reservoir is fine. You only need enough in there to cover the opening at the bottom.
The difference between the low and "full" mark on the reservoir is very small, perhaps only 1/2 qt. or so. It's really not significant so long as the system under the rad cap is right to the top. If you must add any and all you have is distilled water and you don't want to do the rad cap check, then I suggest you do so and then immediately start the engine and go for a drive or at least idle it till the rad fan comes on. This will push expansion fluid into the reservoir, mix with it and lessen the chance of freezing. Seeing the level then rise as it gets hot will also tell you that the system was indeed full. When the engine cools down again, it will draw some of the fluid back in and continuing the mixing inside. A little pure distilled water won't dilute things out to the point that you will lose the proper concentration.
PS. Type II Honda coolant can be purchased in less than 1 gallon jugs. I recall buying it in smaller amounts, but maybe it's just here in Canada.

[repiv]

If it's in storage, don't worry about it till you're ready to start driving it. It won't hurt to be low when it's just sitting there. In the spring, follow my instructions about looking down into the radiator and go from there. Pouring in pure water now would likely cause freezing and result in the reservoir cracking.