An interesting subject.
I don't use any of Redline's products presently, but they are generally very well respected. Yes, the name "Water Wetter" always struck me as somewhat silly. I always figured it might be worth a try, if the rest of a cooling system were all checked out and known to be in good condition, but could still use a little help. Might be a little extra insurance, too, if off on a long haul cross country or were doing some towing, etc. I have one or two bottles of the stuff around here somewhere, but haven't yet added it to any of my cars' cooling systems. Keep forgettin'!
There are a couple new cooling system additives from DEI that make similar claims (
www.summitracing.com is one supplier carrying them). One product is designed for racing, for use only in pure water (anti-freeze isn't allowed by many race sanctioning organizations, which really isn't a big deal since the car's cooling system is drained after each race day or weekend anyway). The other DEI product is designed for street use, with a coolant mix. Their cooling claims looked to be even higher than Redline's, but I haven't seen a detailed tech page on the stuff yet.
As I understand it, straight water is actually better at cooling than water mixed with anti-freeze (glycol). Problem is, straight water is nasty stuff (from the engine's perspective) that, by itself, will cause lots of corrosion in the cooling system, boils more easily and will quickly ruin the bearings in your water pump. Thus, a mix with "anti-freeze" becomes important for other reasons, with some small compromise of cooling effectiveness. I've heard a lot of suggestions to reduce to 25% glycol/75% water to greatly increase heat transfer and still have adequate glycol in the system to handle the other factors. The only real reason to use the traditional 50/50 mix of water and anti-freeze is if the car is parked/stored in really cold temps, something well below freezing. Otherwise, cut back on the glycol and improve coolant mixture effectiveness dramatically.
Note: it also might help to use distilled water instead of tap water, not so much in hopes of improving heat transfer directly, but to reduce calcification and other types of mineral buildups in the engine and rad, which will eventually reduce heat transfer. How much it helps sort of depends upon just how much minerals are in local tap water.
Another idea is to increase the pressure maintained in the cooling system. The Redline page alludes to this in a few places. Triumph figured it out, too. TR3 used a 4 lb. rad cap. TR4 used 7 lb. and TR6 went as high as 12 lb. if I remember correctly. Today some cars use 22 lb. and even higher. Higher pressure raises the boiling point of the coolant mixture and delays or prevents boil-over. The main factor determining how high pressure a Triumph cooling system can handle is the heater core. So, a TR3 (or TR4) without a heater installed can likely run a much higher pressure rad cap safely and really benefit from this. In all likelihood, 12 or even 15 lb. would be safe, were no heater installed. Still, it's nice to have a heater (and defrosters), even if somewhat anemic like the old ones in Triumphs.
Looking at the numbers given on the Redline tech page (referenced above), it appears to claim about 3.5% reduction in temps with a 50/50 mix of water and anti-freeze, and close to 6.5% reduction with straight water. So, if we guess-timate roughly 4.5 to 5% reduction with a 25/75 mix, that's still nothing to sneeze at. For example, that might be the difference between a Triumph running at 185F or 176-178F.
I hope some other folks have some real world tests of Water Wetter to tell us about.
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