Originally Posted By: mechanicx
What 440Magnum says is not relevent or true for pressurized reservoirs. As long as the coolant level doesn't drop below the minimum level in the pressurized reservoir, the pressure is always as high or higher than ambient pressure below the fluid level in the reservior in those systems. A leak won't draw in air into the sytem but only release coolant and the level will drop. Which you should be checking the level periodically on all coolant types and systems. What he was saying just isn't the case for pressurized reservoirs. Air below the cap on a pressurized reservoir is not the same thing as air below the cap in a non-presurized reservoir system.
Good thing he said, "namely cooling systems that use non-pressurized overflow tanks".
Originally Posted By: mechanicx
As far as 440Magnum saying there's no evidence that an OAT like Dexcool shows no advantage. that's not really true either. Dexcool system can look prestine with no buildup inside for many miles even past 5 years even without distilled water. That's not to say G-05 or HOAT is bad or not good too and dexcool is perfect, but there are some slight advantages besides a longer storage life to not having silicates, borates and other things in the coolant.
I have to go back to an old argument you and I were having. The HOATs use a LOW DOSE or either silicates (G-05) or phosphates (Asian). Both provide instant protection whereas OATs such as Deathcool take time to do so. This is a fact that has been documented numerous times. Silicates and phosphates are not as evil as the OAT coolant makers claim. Now perhaps they may have been back in the day since both were present in high doses in conventional American green coolant, but even that is debatable.
Keep in mind both silicates and phosphates essentially do the same thing in regards to providing instant protection which is desirable. The Asians prefer phosphates since their water is not has hard as the water in Europe. Here in the U.S., I think the figure is 80-85% of our water is hard water. However, since the vast majority of both OEMs and coolant manufacturers recommend the use of distilled water (preferred) or deionized/demineralized water, this is not really a big concern.