Water Wetter or Zerex Rad Additive


Got me a Toyota Land Cruiser with a small diesel and I’m thinking of adding some Water Wetter or Zerex to assist with cooling. No problem now, but occasionally in summer when you have the aircon going full and you hit a hill and the turbo kicks in and she tends to heat up.

Has anyone determined that either of these products actually work?


Yes, they work in some applications but they may not do a thing to relieve your car’s problems.

The principle is to reduce water’s surface tension so it can flow easier through long, confined passages. You may have seen some fire engines with the words “Rapid Water” stenciled on the side. Their pumps inject the chemicals into the tanks so the water pressure at the nozzle, hundreds of yards away, is undiminished by the hose’s distance.

If the product is approved for automotive use, try some in your car’s cooling system. Use as directed. It won’t hurt anything. You may see some improvement, maybe not. Be sure to let us know.


Surfactants also help the coolant to maintain surface contact and eliminate localized boiling, especially around the cylinders where the most heat is being generated. I agree that you may not see the benefit in your application but it can’t hurt to try.


Another possibility is adding an additional electric fan on the opposite side of the radiator/condenser.
The wire connector leads would be connected so it would act as a pusher fan.

Some fans are designed to move a lot of air so you might compare the CFM ratings on them.


If this thing is tending to overheating while moving along at a good speed, it appears that the cooling system has degraded (no mileage or age given) or was inadequate to start with. Consider the possibility of adding a transmission cooler if automatic and the cooler is in the main radiator. An oil to air cooler or a bigger rad are also alternatives.


If the car is over ten years old, check the radiator. If you see white or green on the back side, it is the first sign of corrosion on the fins. If any fins are gone, you need a new radiator.


the radiator check seems the most logical suggestion. how about changing the thermostat. (and making sure you have the right one too) if your engine has a antifreeze specification, make sure whatever you add to it is compatible. some antifreeze anti boil (or additives) are NOT compatible with certain metals E.G. aluminum, copper, or brass. so you must make sure what you are adding will not eat out some parts of your engine, turbo, aftercooler, intercooler or radiator.


You should check the small gap in between the radiator, and A/C condenser, for this is the most likely area to get clogged up with debris, yet often overlooked.


Your symptoms are consistent with a radiator cap that is not holding pressure, so that would be the first thing to replace. As for the chemicals, antifreeze does the same thing. This stuff is for vehicles that use water only in the radiator, which you should not do with a modern vehicle.