I use
Sierra antifreeze made by
Peak.
It is an IAT (Inorganic Additive Technology) based antifreeze so it will not harm the gaskets, babbit, rubber, brass, copper, lead, pot-metal, etc found in a stock Model A engine and cooling system. It is also made with propylene glycol (PG) which makes it less toxic and thus safer for humans, pets and wildlife (and yes, I hugged a tree today
).
The down side of IAT based antifreeze (like Sierra) is that it has a two to three year service life before it should be changed out (the IAT corrosion inhibitors degrade in two to three years).
Universal, long-life antifreezes contain OAT (Organic Acid Technology) based corrosion inhibitors which last a long time (up to ten years)...... but being OAT based, it is not something I would put in my stock Model A. Also its long life properties get downgraded to the two to three years when mixed with trace amounts of IAT based antifreeze.
....and by buying "Pre-Diluted 50/50" antifreeze, you are just paying extra for a half jug of water! For a better value, buy the full strength antifreeze and mix it yourself.
....that is my $0.02,
Brad in Maryland