Redline WaterWetter(R) Review

Michael Posner
by Michael Posner
redline waterwetter r review

Inexpensive products that promise significant improvements to your car’s performance are almost always fool’s gold. This is especially true for engine additives (*cough* STP *cough*). However, there’s one company with a sterling reputation for delivering on its promises: Redline Synthetic. Since 1979, the Benicia, California company has been selling coolants, fuel additives and lubricants to the automotive, motorcycle, marine and industrial markets. As part of their range, Redline offer a product called WaterWetter®. They claim their potion can reduce car coolant temperatures by as much as 30ºF. That’s hot! I mean, not.

I reckoned it’d be a doddle to test the bottle. I’d simply run my car sans Redline’s additive and check the coolant temperature. Then, following the instructions on the bottle with my usual precision, I’d give my mount the magic potion, drive the same test loop and measure the temp again.

For the mechanically challenged, installation of WaterWetter® could not be easier. Assuming you can open your hood, open your hood (when it is cold, otherwise prepare for a scalding). Locate the radiator fluid intake point (RTFM if necessary). If you have too much fluid in the overflow tank (above the line labeled max), simply siphon off 12 ounces before installing, as overfilling is a really bad idea. Open the radiator cap (or on most modern cars, the overflow tank) and pour in the full bottle of WaterWetter®, funnel optional.

Before I reveal the results of my test, let’s look at Redline's claims for WaterWetter®'s effects on your cooling system:

• Doubles the wetting ability of water


• Improves heat transfer


• Reduces cylinder head temperatures


• May allow more spark advance for increased torque


• Reduces rust, corrosion and electrolysis of all metals


• Provides long term corrosion protection


• Cleans and lubricates water pump seals


• Prevents foaming


• Reduces cavitation corrosion


• Complexes with hard water to reduce scale

According to Redline, WaterWetter®’s greatest benefits accrue to those cars running straight water in their cooling system– which doesn't include anyone living in snow country. Translation: WaterWetter® offers all the normal protection benefits of regular coolant to people who don't use regular coolant. Oh, at a lower temperature. Well, theoretically…

Strangely, Redline’s own test results don’t square with their ad copy. Their technical literature only shows an eight degree Fahrenheit drop in a car with a 50/50 mix of water and coolant, and an eighteen degree Fahrenheit drop for a car running 100 percent water.

I used a VagCom system (reads sensor data directly from the ECU) for my tests. The pre-WaterWetter® installation delivered temperatures between 96 and 98 degrees centigrade (or 205 to 208 degrees Fahrenheit for the Americans). The post-installation temperature stayed steady at 96 degrees centigrade. Clearly, not the results advertised.

Other websites have tested WaterWetter® and also concluded that the overall decrease in coolant temperature is marginal. So WaterWetter®’s benefits either lie elsewhere (or nowhere). That assessment requires a certain level of trust with Redline products. In my experience, based on their oil products, they deserve this trust.

In reviewing the technical literature on Redline’s website, WaterWetter® claims to reduce hot spots in a car’s cylinder head. In theory at least, this reduces the possibility of localized overheating, improving engine longevity. Supposedly, WaterWetter® also protects aluminum products in the cooling system from excessive heat and cavitation caused by vapor bubbles forming inside the cylinder head and water pump.

In addition, for cars running straight water, WaterWetter® provides some additional protection. This includes traditional coolant roles of reducing corrosion and lubrication of water pump seals. For cars caned on the track or driven in the summer only, a water-only engine and cooling system solution will lead to problems. However, for cars with a tradition 50/50 mix of water and trad coolant, these benefits are already present without WaterWetter®.

WaterWetter® is available at auto parts stores and online for less than $10 a bottle. One bottle is good for an entire cooling system, and lasts as long as you properly keep fluid in your system (assuming you follow the recommended practice of flushing your cooling system every two years or 30,000 miles).

Since WaterWetter® has no readily measurable benefit, should you consider putting this in your car? That depends on your personality and your relationship with your car.

If you’re like me, you like buying stuff for your car in the HOPES of improving power, performance, mileage or longevity (I put Chevron Techron in my tank every 1000 miles). It’s true: I’m a sucker for products that have the POTENTIAL to improve the car, even without any possibility of measuring the results. This is doubly true if the cost isn’t prohibitive and there isn’t any risk of a downside.

In other words, fool’s gold is as good as gold to a fool.

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  • Jdimmers Jdimmers on May 02, 2014

    We are going to use waterwetter in 1 or 2 weeks in our stock-cars with 2.0 pinto engine with plain water in the cooling system and no thermostats. one of the cars has a small cooling problem due to a strong bend in one hose after fixing that we use two 12 inch vans to help in cooling. Will be nice to see engine temp stay at around 95 degrees Celsius without having to use the vans. Modern engines often use special coolants adding anything to that sort of coolant can cause problems, I think Nissan was mentioned with problems they normally use red coolant (at least they do over here in Europe) and VW/Audi use the pink stuff wouldn't ad it to those either. Our race cars are only allowed with plain water and an addition like this that doesn't cause the track to become slippery in case of an emergency

  • Ra60f Ra60f on Mar 22, 2016

    Interestingly what no one here seems to have pointed out is that, if this product does what it says it does, which is (simplistically) improve heat transfer between the engine and the coolant, then the effect of the product would not be measured by only the hot coolant temperature (i.e. As the coolant exits the engine) but by the difference between the radiator inlet and outlet. Theoretically, the coolant entering the engine would be colder than prior to using the product, and the difference between the before and after hot temperature wouldn't mean much. Redline probably uses that number because it's easier for dumbasses to understand and "believe" the product is doing something. In fact, I would even feel better if the radiator inlet temperature went up slightly, because it would mean the coolant was absorbing more heat from the engine components.

  • Cprescott The pandemic changed the sales game. No longer do dealerships need inventory. After two years people are accustomed to having to order what they want and then extorted on the price by the dealer for that privilege. Now used cars with 75k are selling for $5k more than I paid for my 21k, 2016 model back in January 2019. I pray my car won't get totaled and I have but 13 payments left to make on it. I may never buy another car again.
  • Grein002 I hope you meant "take the Ranger out behind the *barn*" rather than "bar". I think something completely different happens "behind the bar".
  • Cprescott Suddenly there is no reason to buy ugly anymore. The Silverdodo is dead. Long live the less hideous Colorado.
  • Cprescott Portable BBQ's for everyone!
  • Lou_BC The 2023 ZR2 is burdened with GM's 8 speed. It's been allegedly "fixed" so it doesn't gear hunt and shudder. I still won't trust it. The turbo 4 cylinder should address the lack of torque found in the V6. I test drove a full-sized Trail Boss. I could make it gear hunt. The turbo 4 didn't seem to be lacking in power, at least for an empty crewcab with a 6.5 box. It lacked anything resembling character. It had next to zero compression braking even with tow/haul engaged. Chevy should have continued offering the VM Motori based inline 4 diesel that's in the older Colorado trucks. I do like the fact that the 2023 comes with 33's standard and IIRC the wheel hubs/axles etc. have been beefed up to handle the larger rubber. The bolt pattern (IIRC) is shared with fullsized 1/2 tons opening up one's choice for aftermarket wheels.
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