I have a 2006 Ford Focus Automatic which is chugging in hot weather and seems to lose some power. I'm hoping, but I am in no way mechanically minded(!), that because it is showing below minimum coolant levels and the weather is very hot, that it's simply an issue with coolant. Can I safely drive in the heat without any additives to the tank, or should I add some tap water for my single journey in the car, which is to buy coolant?

I am HOPING this is the issue causing the check engine light to come on intermittently (in hot weather) and causing a slight lack of power. If anyone can let me know if I'm onto the right path as a first-course of action, that would be greatly appreciated, also. Have checked fuel cap is tight, oil cap is tight, water tank cap is tight, oil levels are good, petrol level is good, no issues under breaking or acceleration with the exception of the above. thanks everyone!

3 Answers 3


Low coolant will not cause a lack of power, but overheating can cause a power loss. This may be causing the check engine light, or it could be a different problem. You can add some water as a temporary measure to get yourself to an auto parts store, while you are there ask them to read your OBD codes, these are on-board diagnostic codes which may give a clue as to what the problem is.

Having low coolant is a concern; coolant doesn't just disappear, so there must be a leak somewhere, or perhaps you overheated and lost coolant then. In any case it's not as simple as refilling it and going your merry way, you want to get it looked at to make sure it's not a serious problem, or a minor problem that could develop into a serious one.

  • Thank you for the replies. I drove and got some coolant (very slowly!) and added it. I will book it into the garage as soon as possible to be checked over.
    – sc00t
    Aug 11, 2020 at 21:13

Drive to the nearest place with the proper antifreeze. Watch your temperature gage. If it gets hot on the way, pull over shut it off and wait for it to cool. Then add the water that you bring with you. If you make it to the store let it cool and add antifreeze. Go to a parts store and have them ready your codes. Then have your cooling system checked for leaks and make sure the fans are working properly and address the codes. Don't let the parts people sell you parts based on the codes , but have it diagnosed properly.

  • Filling with antifreeze before you have found the cause of the leak, in the middle of summer, is just wasting your money, since most likely you will have to drain the system again to fix the problem.
    – alephzero
    Aug 11, 2020 at 16:37
  • It's not really a big deal either way in this instance because the coolant level is only a short ways below the add line.
    – Jupiter
    Aug 11, 2020 at 17:35

The correct answer is: add water.

you may outrun the clock, but without water circulating through an engine block, it will quickly overheat.

overheating is a problem because it causes metals to soften, expand & warp; particularly problematic for a system of interconnected moving parts with little tolerance for error.

likely the cylinders will swell, strangling the piston heads; seizing them in situ.

when everything eventually cools down, the damage will likely already be done. It will be almost as if the once moving parts are welded together; costly and time consuming to recover from.

water is a coolant. the green/red stuff you add to it is a corrosion inhibitor (prevents water from oxidizing, e.g. rusting the metals), and helps prevent water from undergoing a phase change (from liquid to gas/solid, e.g. boiling/freezing).

use distilled (de-ionized) water when possible, but it's not critical in the short term.

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .