A story about how the technical elegance of castor oil turned into the most awkward physiological torture of early motorsport.
🏁 In the 1950s, there was a rule in Grand Prix paddocks that newspapers didn't write about and commentators didn't mention: Formula 1 drivers finished races in completely soaked overalls. Not from sweat—from diarrhea. Juan Manuel Fangio, Stirling Moss, and Mike Hawthorn openly admitted in 1960s interviews: physical endurance in a race was measured not only by reaction speed, but by the ability to endure intestinal cramps at speeds of 250+ km/h for 2-3 hours. Most drivers lost 2-4 kg of body weight in a single Grand Prix from dehydration. This was normal. This was the price of speed.
⚙️ The cause wasn't nerves or adrenaline—the culprit was castor oil. More precisely, Castrol R, the legendary castor oil used as a lubricant and fuel additive for the highly-tuned engines of that era. When burned, it released ricinoleic acid—a toxic substance that entered the driver's lungs through exhaust fumes and caused acute diarrhea. Mechanics knew. Drivers knew. Everyone stayed silent. Because there was no alternative: the mineral oils of that era couldn't withstand the extreme temperatures of tuned engines, but castor oil could.
🔬 Castor oil isn't just vegetable fat from castor beans. It's a natural polymer with a unique molecular architecture: 90% of its composition is ricinoleic acid, a fatty acid with a hydroxyl group in the chain. This group works like a microscopic anchor: castor oil molecules latch onto the metal surfaces of cylinders and pistons, forming a durable film that doesn't break down even at temperatures of 300-350°C. The mineral oils of the 1950s, based on simple hydrocarbon chains, turned into lacquer or evaporated at such temperatures. Castor oil held firm.
🏎️ The Castrol brand got its name precisely from castor oil (castor oil)—the company CC Wakefield & Co began adding it to lubricants in the early 20th century for automobile and aircraft engines. Castor oil maintained viscosity at high temperatures and remained fluid during cold starts—the perfect balance for an era when synthetic oils didn't yet exist. In 1960, the company was renamed Castrol Limited due to this product's popularity. By then, castor oil had become the standard for racing engines: it allowed raising engine speeds above 7000 rpm without risk of piston seizure.
🧪 The problem lay in the combustion byproduct. When castor oil got into the combustion chamber (and it did—as a fuel additive or through the crankcase ventilation system), at temperatures of 800-1000°C, ricinoleic acid partially decomposed and turned into an aerosol. This aerosol exited through the exhaust pipe, mixed with air in the cockpit, entered the driver's lungs. Ricinoleic acid is a powerful laxative, known to medicine since ancient times. A dose of 10-30 ml of castor oil causes diarrhea in an adult within 2-6 hours. Drivers inhaled microdoses of this acid throughout the entire race. The effect was predictable.
⚡ Drivers couldn't close the cockpit—the open cars of the 1950s had no sealed cabins. They couldn't refuse castor oil—competitors used it, and falling behind in engine power meant losing. They couldn't stop in the pits—every second on track decided the race outcome. So they endured. The physical preparation of a driver in that era included not only training hands and neck, but the ability to ignore intestinal cramps while sitting in a scorching metal capsule at speeds where any mistake cost a life.
💀 The most brutal test were the long races. The 1955 Monaco Grand Prix lasted 3 hours 23 minutes—100 laps of a narrow street circuit without a single straight, where the driver turned the wheel every 5-7 seconds. Maurice Trintignant, who finished ninth, later admitted: after the 50th lap, the cramps became so strong that he couldn't fully depress the brake pedal. He braked in short pulses to avoid aggravating the pain in his stomach. This wasn't heroism—it was physiology versus engineering.
🌡️ Fangio, five-time world champion, said that by the end of a race his overalls weighed twice as much as at the start. Dehydration led to dizziness, but stopping was impossible—each pit stop took 30-40 seconds, enough to lose position. Paddock doctors recommended drivers drink salt water before the start to compensate for electrolyte loss, but this only delayed the inevitable. Castor oil worked like a chemical timer: the longer the race, the stronger the effect.
🔥 Mechanics tried to reduce the concentration of castor oil in the fuel mixture, but this led to engine overheating. The Ferrari and Maserati engines of the 1950s were tuned to 250-280 hp with a displacement of 2.5 liters—specific power of 100-110 hp/liter, extreme for naturally-aspirated engines of that era. Without castor oil, pistons began scoring cylinders after just 20-30 laps. So the concentration of castor oil in fuel remained high—10-15% by volume. This was a compromise: either the engine or the intestines. Drivers chose the engine.
🧬 Salvation came not from medicine, but from petrochemistry. In the late 1950s, engineers began experimenting with synthetic oils based on polyalphaolefins (PAO) and esters. These substances were created not from plants, but from chemical reactions: hydrocarbon molecules were arranged in strictly defined chains that didn't break down at high temperatures. The first synthetic oils appeared in aviation—jet engines required lubricants capable of working at -50°C at altitude and +300°C near the turbine. By the early 1960s, this technology came to motorsport.
⚙️ Mobil 1, the first commercial synthetic oil, was introduced in 1974, but racing teams began using experimental synthetic formulations as early as 1962-1963. Ester oils provided protection comparable to castor oil at extreme temperatures, but didn't release toxic combustion products. Ricinoleic acid was no longer in the exhaust. Diarrhea disappeared. Drivers stopped losing kilograms per race.
🏁 The transition was quick and invisible to the public. In 1961, Castrol introduced a new line of synthetic racing oils, keeping the legendary Castrol R name but removing castor oil from the formula. By 1963, all leading Formula 1 teams had switched to synthetics. Old drivers recalled the castor era with dark humor: Moss once said that modern racers don't know what real endurance is—they don't drive in soaked overalls with intestinal cramps at 250 km/h.
🔬 Today, castor oil is no longer used in motorsport, but its legacy lives on in petrochemistry. Modern racing oils are multi-component synthetic compositions based on PAO and esters, capable of operating at temperatures up to 400°C and providing stable viscosity in the range from -40°C to +150°C. Formula 1 in the 2020s uses oils with viscosity 0W-20, which reduce engine friction by 15-20% compared to mineral equivalents—this gives an additional 5-8 hp without changing the engine design.
🏎️ Castrol remains one of the largest oil suppliers for motorsport: the company has been a partner of the Aston Martin team in Formula 1 since 2021. Modern Castrol EDGE, used in racing, doesn't contain a drop of castor oil—it's a fully synthetic product based on titanium compounds that strengthen the oil film under load. The brand name recalls the castor era, but the technology has moved 70 years forward.
📚 The story about castor oil and diarrhea became part of the paddock's oral tradition—it's told to young drivers as a lesson about the price of speed in the early years of motorsport. In 2019, the Monaco Grand Prix held a retro parade featuring 1950s cars, and several veteran mechanics filled the engines with real castor oil—for authenticity. The exhaust smell was sweetish, thick, unmistakable. Modern drivers wrinkled their noses. The old-timers smiled: they remembered that this smell meant not only speed, but 3 hours of intestinal cramps in a scorching metal capsule with no right to stop.