Most coolants now days are silicate free. It will tell you right on the labels. I called Prestone once many years ago and they told me they hadn't had silicates in their anti freeze since 1995 except in one diesel coolant. Dex Cool Extended Life (orange) is silicate free.
https://www.carid.com/articles/antifreeze-explained.html
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'Silicates are a chemical compound containing silicon, oxygen, and one or more metals, e.g., aluminum, barium, beryllium, borate, calcium, iron, magnesium, manganese, molybdate, nitrite, nitrate, phosphate, potassium, sodium, or zirconium. Silicates may be considered chemically as salts of the various silicic acids. 1 In a cooling system, silicates offer metal parts ( especially aluminum ) a high level of fast acting protection against corrosion and pitting that is vital. Silicates "charge up" a cooling system with protection that lasts about 2 years. After two years, the coolant mix needs to be replaced with new coolant and water. New every two.
Silicates offer instant protection to the cooling system. Heavy duty vehicles rely on silicates to give precise amounts of protection, and can be recharged without draining the entire coolant. Silicates do have a life, and it's a short one - two years. If left longer, build up inside the radiator begins, and the silicates actually contribute to cooling system problems. Silicate drop out occurs after the coolant has been "spent", and the inhibitors drop out of solution. Silicates are blamed for deposit build up in radiators and heaters, causing engine overheating and poor heater performance. Once the silicates drop out of solution, dissimilar metal corrosion is no longer suppressed, and metal components begin to deteriorate.
Silicates are deemed to be abrasive in a cooling system, and are blamed for premature water pump seal failure. With the average miles per year per car on the rise, it does seem to be a valid concern. "
Roger Lee
LSRM-A & Rotax Instructor & Rotax IRC
Tucson, AZ Ryan Airfield (KRYN)
520-349-7056 Cell
