Hi from the Netherlands, I have a 2015 Honda Accord 2.2i-DTEC Executive AT. I bought it new. With about 55,000 km it still looks like new.
I have one question and I know it's a bit stupid, but please don't judge me, I'm not a very technical type and I don't want to go to Honda service before the next oil interval just because of this.
The thing is the engine coolant is close to the MIN mark. I checked the owner's manual and it's still unclear to me. What should I add, just distilled water?
Thanks!

 

You could just add distilled water, but that will dilute the anti-freeze very slightly. Probably about 7 liters total, so if you add 300ml that will change your 50/50 mix into 48/52 which is not worth worrying about unless you lived 700 km farther north.

Here in USA it's common to find pre-mixed antifreeze as well as concentrated. You mix the concentrate about 50/50 with water, or else use the pre-mixed stuff directly. Take your pick, or whatever is readily available.

The main ingredient is always the same, but it's the anti-corrosion additives that may or may not be compatible. I think Honda says to use something without silicates. Safest is to buy a bottle from the Honda dealer parts department.

Around here (USA) the common types are DexCool and hybrid-OAT. The hybrid-OAT seems to be compatible with almost everything, while the DexCool is GM's favorite flavor and it not very friendly mixing with other types.