Proper coolant for a 1974 Audi Fox (B1)
 

Nothing special about a coolant choice. The newer formulas are very good compared to the antifreeze of the 1970s. I would suggest using any name brand All Makes All Models antifreeze. I use Prestone AMAM in my 1991 Vanagon with no issues.

I think you need to ID what's in the car presently. That would influence what you do going forward. Co-mingling fluids can cause all sorts of issues in these cars.


The earliest VAG coolant I'm aware of is called G11, it's a blue-green color. They transitioned away from that around 1995 or so. On most of the modern cars, you can find something like "G11" or "G13" printed on the coolant bottle. The Owner's Manual would be another point of reference.

vendor says:This is the newest version G13E as recommended by Audi/VW for all models per specification TL052774J. Can be used in place of all the older purple, red, and lilac colored antifreezes (G11, G12, G12++). The Pentofrost E is designed for all modern high performance aluminum engines. It contains silicate and is nitrite, amine, and phosphate free, neutral to metal, rubber, and sealing materials.

With a metal waterpump impeller, you ALWAYS want a coolant with silicate. This rules out any Dexcool-compatible or G-12.

For the 1974 Audi Fox, high silicate "HD" coolant for diesel trucks would be closest to original, but in fact the newest coolants on market do have silicate and are also "hybrid" with Organic Acid Tech coolants, like Dexcool/G-12. So those are the only ones to avoid, any Dexcool-compatible. New VAG coolants G-12++ are compatible and do have silicates. A few years ago I would have said "G-05" a hybrid coolant, but now a product like Valvoline is the same or better.

No other additive protects metal impellers from cavatation pitting and subsequent corrosion as fast as silicates. Mercedes believes in them strongly enough to include a sack of it in the reservoir tank to replenish the levels.

This was the purpose of plastic impellers, to allow unsilicated OAT coolants to be used. Now, they are obsolete. People with newer vehicles who sought out metal impeller pumps must not use the orig G-12 coolant. Same for the 1974 Fox.