In automotive coolants, what do manufacturers use as antifreeze?

Prepare for the Automotive Service Technician Period 1 exam. Study with flashcards and multiple choice questions, each question has hints and explanations. Get ready for your exam!

Antifreeze in vehicles is made from glycols, which lower the coolant’s freezing point and raise its boiling point so the engine isn’t damaged in cold starts or extreme heat. The standard antifreeze options are ethylene glycol or propylene glycol because they mix well with water, stay liquid over a wide temperature range, and allow the use of corrosion inhibitors to protect the cooling system components. Methanol is toxic and less durable as an automotive coolant; water alone freezes and boils at the wrong temperatures without the glycol, and glycerin isn’t as effective or cost-efficient for automotive cooling. So the best answer is ethylene glycol or propylene glycol.