Which statement about long-life anti-freeze is correct?

• A. It can cause silicate drop-out
• B. It is always compatible with all materials
• C. It has no potential issues
• D. It is never used in diesel engines

Answer: (A)

Long-life anti-freeze relies on extended inhibitors to protect metals over a longer period, but its additives can interact with other coolant chemistries and with the system’s materials. Silicate drop-out means solid silica-containing particles precipitate out of the coolant and settle in the passages. This can happen when a long-life formulation is used with incompatible coolants or when the chemistry degrades over time, causing the silica-containing components to precipitate. The result can be clogged passages and reduced cooling efficiency, which is why this option is the best choice.

It’s not true that long-life coolant is always compatible with all materials, nor that it has no potential issues, and it is indeed used in many diesel engines, so those statements aren’t correct.