Why Car Brands Used Sperm Oil In Transmission Fluid Until The 1970s

Anyone who's a vegetarian already knows that animal products can turn up in surprising places. Beef fat in dryer sheets? Check. Fish scales in nail polish? Sure. But you've probably never considered whether your transmission fluid might contain animal products. Happily, it doesn't. Unless you're a time traveler from the 1970s, no animals were harmed to lubricate your car. But before 1972, it was common practice. 

Until then, transmission fluid used sperm oil. Sperm oil, which is actually a wax ester collected from the spermaceti organ in sperm whales' heads, was incredibly useful as a lubricant in transmission fluid. It reduced friction, stayed stable under high heat, prevented rust, and didn't break down easily, helping transmissions run smoothly and last longer. Unless there was a major fault with the car, you would never need to change your transmission fluid. But the sperm whale was added to the endangered species list in 1970, and car manufacturers were told they needed to find a replacement by 1973. 

Outlawing the use of sperm oil in transmission fluid was undoubtedly a good thing. Without the ban, sperm whales would probably have been hunted to extinction. Of the 55 million pounds used each year, over half was destined for car lubrication. Mobil alone used 15 million pounds of sperm oil a year. So, cars stopped using sperm oil, the whales lived happily ever after, and that was the end of the matter. Except it wasn't. Because without sperm oil, the car industry had big problems.

Once sperm oil was banned, the automotive industry scrambled to find a substitute. The first replacements included synthetic esters and other natural oils, but they couldn't match sperm oil's performance. Mid-1970s newspaper reports described how early substitutes caused corrosion of the fittings between radiators and cooling units, allowing oil to leak into the cooling system and antifreeze to leak into the transmission.

Before the ban, fewer than 1 million annual transmission failures were reported in the U.S. By 1975, the number had ballooned to over 8 million. Manufacturers worked quickly to develop a suitable replacement. Companies like General Motors and Ford have reformulated their branded transmission fluids multiple times since the 1970s, but one of the earlier alternatives was jojoba oil. This was a liquid wax ester, like sperm oil, which made it a direct replacement in terms of molecular structure and performance. However, supply and cost constraints made this an unsustainable option.

Popular transmission fluids now use fully synthetic compounds, including paraffin, solvents, and anti-oxidant dispersants. Current formulas are more advanced than ever to meet the demands of today's high-performance vehicles. They're better than their sperm oil predecessors and a significant improvement on the substitutes that caused issues in the 1970s. The sperm whale still faces threats like climate change, ship collisions, and noise pollution, but at least it's no longer being killed just to keep our cars running smoothly.