Antifreeze for Your Model T 

By Don Mitchell

Back in September, Kirk sent out an email that had been forwarded to him with an article from the Rolls Royce Club newsletter attached. The article discusses the effects of modern (currently used) antifreeze on older cars. It apparently attacks lead which is part of the solder used in Model T radiators so they are definitely susceptible. It also attacks silicone compounds, such as gasket sealants. I checked my antifreeze and found, not surprisingly, that it was the modern stuff and therefore something I shouldn't be using. I had bought it and put it in my '27 Tudor without knowing it could cause problems. The article mentions that the change in antifreeze was made with little or no publicity so few people know about the problem.

The current antifreeze is made using an Organic Acid Technology (OAT) corrosion inhibitor which was introduced about 1995. Previously, antifreeze was made using an Inorganic Additive Technology (IAT), referred to as conventionally inhibited. The change was apparently made to extend the life of antifreeze. The problem is that the information about which type of inhibitor is used does appear on the labels of antifreeze containers. Also, the color of the antifreeze can not be relied upon to identify which ones are safe to use in older, i.e., 20th century cars.

The good news is that IAT antifreeze is still available. The article recommends Sta-Clean Antifreeze. It is propylene glycol based antifreeze which is made in California. Because it is propylene glycol rather than ethylene glycol based it is more environmentally friendly (less poisonous), but it is not available locally. It appears it can be ordered through their website or one of their distributors. There are ethylene glycol based IAT antifreezes which are available locally. Zerex Regular Green is available at NAPA. Peak PKAOG3 is also an IAT antifreeze which they told me by email is available at AutoZone and NAPA. I couldn't find this antifreeze on the NAPA website for a local store or at AutoZone, which does have other PEAK antifreezes. I did find an IAT antifreeze at AutoZone which is called AutoZone Conventional Green. That's what I bought and used to replace the antifreeze in my Model T.

If you have any doubt, I suggest you change the antifreeze in your T. The AutoZone antifreeze costs $10 a gallon which is a lot less than a radiator or coolant system repair. You will need two gallons. Model T cooling systems hold three gallons so you need two gallons of antifreeze to make a 50% antifreeze/water mixture (l.5 gallons antifreeze, l.5 gallons water).