rover4x4 said:
Ive heard it makes vehicles run cooler. My research seems to indicate its low on silicates which seems to be a good thing.
Cooler? Maybe, but not because of heat transfer properties, but cavatation....
The Japanese are the ones pretty adament about NOT using silicates in their coolants. This dates back to about 1980 when silicates were first used and caused early water pump seal failures. It did not cause gross leaks, it just caused them to seep or "weep". But that is enough to contaminate the pump bearing and eventually cause it to fail also. Phosphates reduce cavitation erosion and I assume this is a major reason the japanese retained phosphates in their OAT coolants. Might be BMWs thinking, I dont know.
In high levels, silicates tend to gel and settle into cooler areas of the cooling system. Ford had a rash of TSBs/recalls to address this exact issue. The gel inhibits heat transfer and coolant flow. The silicates also form abrasive compounds that do damage. The low volume cooling systems that are now common are more sensitive to these problems than older cars. Silicates provide the fastest acting aluminum protection. But this fast acting protection is not needed in most cars unless abrasives have already formed. Except in extreme cases (IE: aluminum oxide contamination) low silicate levels are more than adequate. There are many zero silicate coolants (Toyota, Honda, etc) that have proven themselves to provide excellent protection.
Water pump cavitation becomes a bigger problem under severe service conditions like heavy loads, high rpm, rapid engine accelerations. More likely in the "Ultimate Driving Machine." then a Rover. In some engines this is exagerated by a combination of cold ambient temp and heavy load because of the reduced radiator flow. Cavitation damage is worse in aluminum components. Water pumps are most common but intake manifolds, etc, have been destroyed by cavitation.
Using Gallon jugs of distilled water (To insure freshness) is the way to go. The potential problem comes with longer service intervals and silicate free phosphate free coolants. These coolants are already lower pH and do not have silicates or other sacrificial additives that are included in conventional coolants. This makes it more likely for them to have problems near the end of their life cycles. Leeching minerals directly from engine components is a pretty remote and extreme example. It does occur in industrial cooling systems but is not likely to ever happen in any 50/50 coolant/water mix. I did see a couple of examples that appeared to be leeching problems, but in one case cavitaion due to a combination of performance modifications is a more likely explanation and the other appears to have be a bulk water storage problem (carbonic acid).
Peak Global Lifetime is another good antifreeze.
