Naveen Kumar g
•6hCan I add water and coolant separately, such as water in the radiator and coolant in the coolant reservoir?

Autocar India
No, do not add water to the radiator and coolant in the bottle separately. The radiator and the coolant bottle are part of the same closed system, so they mix anyway. You should use the same mix in both places, as per your owner’s manual - most cars need a 50:50 mix of coolant and distilled water. The easiest way is to buy premixed coolant and top up only with that.
Many newer cars don’t want you to open the radiator at all; you top up only in the coolant bottle to the MAX line when the engine is cold. Check your manual.
If you must top up in a pinch, use clean distilled water, but if you can only use tap water, use only enough to get you home. Then get the system drained and refilled with the correct mix soon after.
If the level keeps dropping, there is likely a leak or a weak cap - get it checked. When you buy coolant, stick to the type your car brand recommends.
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Posted on: 12 Apr 2026
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