Thanks for all the kind advices!

​​​​​​​The reservoir is fine and is working fine. This is my first time refilling the reservoir and it's been over a year. I do keep the coolant level checkd every week and sure that my radiator is fine. No temp. issues with the s2 and still drives like the first day I brought it home.

 

There are differences. From Honda:


Honda has sent the information attached below to its dealers. While you might not expect the source to be exactly unbiased, it does provide technical information and justification for differences in their formula.


Genuine Honda Coolant is the Only Way to Go

Increasingly severe operating conditions and the advent of lower maintenance requirements have resulted in significant changes in the variety and the concentration of additives used in engine coolant. Also, the continual improvements in engine and vehicle design have challenged coolant suppliers to design products that perform well in a more demanding environment.

To meet these needs, Honda engineers have developed a superior, high-quality coolant that has several advantages over the competition.

Some antifreeze, although labeled as safe for aluminum parts, may not be compatible with Honda/Acura cooling system components. Extensive research and testing by both Honda R&D and CCI, the manufacturer of the Honda coolant, have proven that the abrasive silicates and/or borates found in most domestic coolants can cause these problems:

- - Silicates bond to the surface of the water pump seal and act as an abrasive, causing considerable seal erosion and coolant leakage. In actual tests, the silicated coolant caused early leakage. This leakage increased dramatically until a substantial portion of the coolant had been lost. In contrast, the Honda coolant had almost no leakage through the duration of the test.

- - Silicates tend to gel and settle in the coolest parts of the cooling system, causing radiator plugging and overheating.

- - Borates cause pitting corrosion on the cylinder head.

- - Silicate inhibitors are difficult to stabilize and, therefore, limit coolant shelf life.

Most commercially available coolants were originally designed for cast iron engines. Silicate, an inexpensive additive, was added to coolants to prevent aluminum corrosion, but the long-term durability of the combination was not tested.

In contrast, Honda coolant was designed specifically for aluminum engines. It contains an organic corrosion inhibitor instead of silicate. This superior formula gives these advantages:

- - No silicate abrasion of water pump seals. For example, these graphs show the surface roughness of two aluminum water pump seal rings. Seal A, exposed to silicated coolant, shows considerable damage. Seal B, exposed to Honda coolant, displays only minute wear.

- - No plugging or overheating caused by silicate gelling.

- - Excellent corrosion protection for aluminum components.

- - Long-term corrosion protection for other cooling system materials (steel, cast iron, copper, solder, gaskets, seals, and O-rings).

 

^^ i skimmed over that. But ya oem Honda stuff is ++++++

 

Honda Type 2 or Toyota pink coolant, both use pretty much the same composition.

 

I used Toyota pink coolant to replace the coolant in my Tacoma but I wondered if I could have used Honda and just kept my inventory of partially used bottles down a bit. Prolly the same stuff with a different color for distinction.

 

It's hard to get a 100% answer but from the research I have gathered I wouldn't hesitate to use just one of them on both cars.
Pick the color you like best or whichever is cheapest and easiest to get

 

For emergency use, I have a couple liters of Sterile Water purloined from work. Figure it's better than generic anti-freeze or drinking water...

 

Distilled water from the grocery store is cheap...

 

Not sure what the water you have really is, other than sterile, but it will work short term. Distilled, not purified, is best and cheap at the grocery store as mentioned above. I use a UV C band water sterilizer (Steri-pen) to sterilize any non-turbid water backpacking as well as trips to India and other places sanitation is a little shaky. UVC can sterilize to FDA standards. I have a commercial UVC band light incorporated on my well water filtration system. However the water is still loaded with minerals and I would never throw it in my radiator or battery.

 

'00 cars came with old style green coolant that needed periodic changes or a full flush to change to another type. I did a good flush and switched to Prestone long life coolant (which is Silicate free) and it works just fine. I drain and put in a fresh gallon every five years and expect no problems.