By on January 29, 2008

0601_hppp_24z2003_pontiac_grand_prixredline_water_wetter.jpgInexpensive 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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27 Comments on “Redline WaterWetter® Review...”

  • avatar

    A properly operating car has a thermostat that regulates how much coolant enters the radiator… coolant too hot and as much coolant goes in to get cooled; coolant not yet warmed up and the thermostat shuts down circulation so that the coolant in the engine block gets a chance to warm. I’ll bet your thermostat is calibrated to 96 degrees and since neither of your tests overwhelmed the radiator’s cooling abilities you got no additional cooling benefit because none was needed.

    You need to try your tests with a car that has known overheating problems. My car, for example, heats up a bit if you are idling with the air conditioner on. However, I’d rather not try experimenting on my C43 AMG thank you very much.

    In addition to corrosion protection and freeze protection, antifreeze also increases the boiling point of the coolant, thus allowing you to not build too much pressure when the coolant temperature is a few degrees above 100 C.

  • avatar

    I run water wetter and it’s competitive equivlent MotorMax in my 2 racecars (a Honda Civic and a Porsche 944). What I find is that they do not make a substatial difference in lower the overall temperature but more importantly they make the cooling system more effective overall – they most importantly help reduce the “hot spots” that cause failures in gaskets and warping of the head. This more consistent cooling effect is just as important as reducing the overall temperature. Though not as marketable reason.

  • avatar

    I don’t disagree, and I do think it is a good product, but they advertise right on the bottle…up to 30 degrees cooler, live by the word die by the word…


  • avatar
    Stephan Wilkinson

    The business of flushing and refilling a car’s cooling system–whch I used to do religiously–is for many cars outmoded, because they have permanant coolant fills.

  • avatar

    You’d have to try this test under controlled conditions with the thermostat removed (as Sunnyvale mentioned).
    If it provided a noticebly reduced operating temperature over a plain 50/50 mix, then the claims made about more consistent adhesion of the coolant to the metals of the cooling system might “hold water”.
    The real test would be to monitor the knock sensor while running the vehicle under “summer” conditions. Less knocking would indicate the the cylinder heads were receiving better (more even) cooling.

  • avatar

    You better take that VW & get it flushed. WaterWetter can make quite a mess when mixed with G12.

  • avatar
    johnny ro

    down 30 is not clearly stated as “down 30 on your dashboard” so lets not call them liars but it is a bit misleading ad copy.

    It includes down 30 at hot spots. OK.

    Who has not read worse, I remember car ads suggesting my sex life would improve with the car in the ad.

    No benefit for normal car in normal use. On track, OK. Not in any modern VW/Audi for road use.

  • avatar

    Shaker: I agree a controlled test would be more revealing. Redline shows a controlled test on their website and it is no where near the copy on the bottle…so I had to knock them off that claim.

  • avatar

    Watter Wetter works as advertised when using straight water. It is a staple for those who race small block Chevys across the land. We use it in my sons race car to keep the temperature down and it recently solved an overheating condition on his S-10 V8 (running straight water in the summer). Don’t mix it with antifreeze and remember to take it all out and put in antifreeze if you want to use the engine in the cold weather.

  • avatar

    FWIW, I used it on my eagle talon TSI AWD with a huge front mount that blocked flow to the radiator and caused the engine to start to get hot on summer days in traffic. Water Wetter didn’t seem to change my situation any. I was still using a 50/50 mix of antifreeze and water.

    • 0 avatar


      Wud up fellow dsm owner. I also have a huge front mount on my dsm and I have been troubled by my car overheating. I was wondering if you had any suggestions. FYI: I live in IL and i have also opened up the bumper wider on the eclipse…still have heating problems. I dont want to eliminate my ac condensor but i may have to.


  • avatar

    As SunnyvaleCA pointed out, the reviewer’s test is not particularly meaningful as long as the vehicle’s cooling system is adequate because the thermostat would regulate the coolant temperature.

    Perhaps an infrared thermometer directed at different parts of the cylinder head would show a difference in the before and after tests, because WaterWetter claims to reduce localized hot spots.

    I tried a bottle of WaterWetter in one of my cars which had a marginal cooling system (temp would creep up when idling or in city driving). It seemed to make a difference, but I didn’t drive the car enough to really tell for sure. It’s certainly not a panacea.

    I later used a rad flush product to clean out rust and mineral build-up from the cooling system, and I’d say this helped the problem much more than the WaterWetter had. If I continue to have cooling problems, I would be tempted to try it again though.

  • avatar

    I’ve used WaterWetter in one of my ranch trucks – it has a modified big-block and has always been hard to keep cool – and with a 50/50 antifreeze solution it did drop the temperature perhaps 5 degrees or so. Not a huge difference, but it does appear to help. Between the WaterWetter, some fan shroud modifications and a new fixed-blade high flow fan it made the truck driveable in 90 degree weather…and in degrees per dollar, the Redline was probably a decent investment. It doesn’t work miracles, but it’s cheap enough to experiment with (and a lot cheaper than a new custom radiator).

  • avatar

    …or there’s the cheap autocrossers’ trick: ice-cold water radiator flush between runs.

  • avatar

    So what exactly is the science behind this stuff? Seems pretty implausible

  • avatar

    One of the biggest reasons to run WaterWetter at the track INSTEAD of coolant is for safety reasons. If you blow a coolant hose, you won’t dump super slippery coolant all over the track and cause a potentially dangerous situation for the cars running behind you. I have seen too many indidents resulting from cars hitting coolant puddles and then careening off track. WaterWetter is not slippery like coolant and is much safer for your fellow racers.

  • avatar

    A Honda Civic Race Car. Thats damn funny!

  • avatar

    I use Water Wetter religiously in my straight-water run turbo’d 240z. It has helped out some in addressing hot spots in the head.

  • avatar

    It works best with a straight water, which is what I run in my Miata Solo racer.

    “So what exactly is the science behind this stuff? Seems pretty implausible”

    It’s what’s called a wetting agent. It alters the surface tension characteristics to what it’s added.

  • avatar

    “A Honda Civic Race Car. Thats damn funny!”

    There’s a Spec Honda series, although I think it’s for the CRX. Regardless, there are a lot of classes in club racing for cars other then Vettes, Vipers and Porsches.

    Could also be in IHRA drag racer.

  • avatar

    DO NOT run water wetter. i ran it just like it said water and water wetter. The water still Boiling when hot busting my coolant hose cracking my head gasket and ruining my head. I say stick with coolant i had a slight problem with my temp go up in traffic. Now I have no transportation. this product sucks!!!!

  • avatar

    I recently drove from California to Kansas in our 2000 Nissan Pathfinder. Before leaving I took all the precautions and changed the fluids, added Z-Max to the fuel system and engine and added WaterWetter to the cooling system. Halfway into the trip the temp gauge started bouncing from normal down to cold and everywhere in between. It wasn’t overheating, but I contacted my mechanic on the phone anyways. He suggested that it was a problem with the thermostat and just keep an eye on it. Long story short, we made it to Kansas and I had the thermostat replaced as soon as I could. The mechanic there indicated that there was some sort of silicone type goo on the thermostat that was causing the problem. Since the radiator was new and all the coolant was fresh (50/50 mix), my conclusion was that the WaterWetter product somehow gummed up the system and cost me $280 in repairs. Hopefully, this is my only repair. Never again will I use this product in any of my vehicles.

  • avatar

    Just wanted to add: antifreeze doesn’t wear out, that was not covered nor mentioned. It’s the additives that are “used up” in use, using a product like water wetter (just read the 1st post here, I may consider another product means you don’t have to change your coolant.

    With a thermostat and proper (read: effective) cooling system, you would never notice the temp benefits of water wetter or the like. But if borderline, it COULD help. Still a band-aid, but better than nothing.

  • avatar

    I can’t say that it works as advertised but I use it in my 98 Jeep 4.0 and it reduced the temp by 10 degrees, I also have used it in 468 Chevy BB engines and it also worked to reduce by 10 degrees and stabilize the temperature especially in 90 degree weather and stop and go traffic.

    This is my experience and I stand by the product. “Purple Ice” works just as well also.

    Running 50/50 mix in all.

  • avatar

    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

  • avatar

    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.

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