Content ID


Antifreeze Differences

Not long ago, I was cruising the internet for restoration advice. A “tips” column at one site discussing antifreeze caught my eye. This particular exchange debated the use of today’s extended-life antifreezes in antique tractors.

Intrigued with the debate, I sought out the advice of expert Carmen Ulabarro, a coolant specialist with ChevronTexaco.

Test to Keep or Replace

Granted, Ulabarro works for a company that sells coolant, but he proves his trustworthiness by advising collectors to test radiator fluid quality to see if it needs replacement. Notice Ulabarro uses the term coolant as opposed to antifreeze. “Way back when engines were simpler, the primary goal of radiator fluids was to prevent engines from freezing,” he says. “Today, coolants are crucial for heat transfer and for corrosion protection, as well.”

This explains why radiator solutions no longer employ methanol, which worked well to prevent water from freezing. Come summer, methanol tended to boil over.

To solve this problem the automotive industry switched to glycol as the base for coolant. Glycol works great as an antifreeze, but it isn’t very good at conducting heat from the engine to the radiator.

H20, on the other hand, excels at this job. This explains why you shouldn’t use pure coolant in a radiator. This practice can cause an engine to run at the wrong temperature. Water also activates the chemicals that protect against rust and corrosion.

The glycol in antifreeze is either ethylene glycol (EG) or propylene glycol (PG). What are the differences between the two?

EG, which is the most commonly used coolant base, is more toxic than PG. Otherwise, the differences are nominal.

Whether a coolant has an EG or PG base, what really separates a coolant is its chemical composition.

Inorganic vs. Organic

Coolants commonly used in older engines, such as those in antique tractors, use Inorganic Acid Technology (IAT) that provides a life span of two years or 30,000 miles. IAT coolants are typically green in color.

Coolants with Organic Acid Technology (OAT) composition, introduced in 1994, have an extended life span of five years or 150,000 miles. OAT coolants come in a variety of colors.

To make things more confusing, today there are hybrid combinations of both IAT and OAT compositions.

Finally, coolants are often classified by their type of use: automotive, heavy-duty, and universal (for both car and heavy-duty engines). Differences between these classifications are often determined by the level of additives they contain to protect against rust and corrosion.

Confused? To simplify your choice of antifreeze, follow this general rule of thumb:

For antique tractor engines, use green IAT coolants rated for light-duty or universal use. When it comes to high-power modern tractors as well as today’s cars and trucks, go with the manufacturer’s coolant recommendation.

Get detailed tips on coolants and their use at

Read more about

Machinery Talk