Motor oil is used to lubricate and protect your vehicle from wear and tear caused by heat and friction. Yet, despite its protective properties, motor oil is full of ingredients that can cause people and animals harm when touched or ingested. So, yes, motor oil is toxic to humans and animals. Let’s discuss the extent of that toxicity and how to protect yourself and the environment from exposure.

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Understanding What Makes Motor Oil Toxic

In order to understand how motor oil is toxic to humans and animals, you must know how it is made. Rather than motor oil’s chemical makeup, it is its physical substance that is the issue. Engine oil is a hydrocarbon, a compound composed of hydrogen and carbon atoms. Hydrocarbons come in various forms, yet they all share an oily texture when in their liquid state. The peril arises when these oily substances are ingested, as they have the potential to enter the airway or be inhaled during vomiting—which is known as aspiration.

Aspiration can be incredibly irritating and may lead to infections. The proximity of the airway to the esophagus plays a pivotal role, and the concept of viscosity (a substance’s flow properties) comes into play—hydrocarbons with low viscosity (thin consistency) are more likely to be aspirated than those with high viscosity (thick consistency).

So while motor oil tends to have viscosity, it also has fumes that can be irritating as well.

The Toxic Contaminants in Used Motor Oil

Used motor oil introduces an additional layer of concern due to the presence of contaminants that are absent in fresh oil. The exposure of motor oil to high heat in operational vehicles leads to the formation of new chemicals that can be more toxic than the oil itself.

Moreover, as the engine oil circulates through the motor’s moving parts, it begins to collect heavy metals and other contaminants. This is why proper disposal of used motor oil is so crucial to protecting the environment. These harmful substances present in used motor oil, including benzopyrene and polycyclic aromatic hydrocarbons (PAHs) are highly toxic and carcinogenic.

How Motor Oil Affects Humans and Animals

Here is a glimpse at what happens should you or another living thing consume, touch, or inhale motor oil—both new and used:

  • Defatting. Motor oil on the skin may lead to defatting, which involves the dissolution of fats and oils in the skin, removing the protective layers.
  • Allergic reactions. Reactions can manifest as itching, redness, hives, or even a rash.
  • Respiratory irritation. Inhaling motor oil fumes or vapors can lead to irritation of the respiratory tract. This can result in symptoms such as coughing, wheezing, shortness of breath, and a feeling of chest tightness.
  • Dizziness and nausea. Exposure to high concentrations of motor oil fumes can cause symptoms like nausea, dizziness, and headaches.
  • Gastrointestinal distress. Swallowing even a small amount of motor oil can lead to nausea, vomiting, stomach cramps, and diarrhea.
  • Cancer risk. Prolonged exposure to used motor oil, especially through skin contact, can increase the risk of skin cancers and dermatitis. Some components of used motor oil, such as polycyclic aromatic hydrocarbons (PAHs), are known carcinogens.

Precautions and Safety Measures When Handling Motor Oil

Given the potential risks associated with motor oil exposure, it’s essential to take proper precautions when working with motor oil or being in its vicinity:

  • Use Protective Gear. When handling motor oil, wear appropriate protective gear such as gloves, safety glasses, and long-sleeved clothing to minimize skin contact and prevent accidental splashes.
  • Proper Ventilation. Ensure that the area where motor oil is being used or stored is well-ventilated to minimize the inhalation of fumes.
  • Avoid Skin Contact. If motor oil comes into contact with your skin, wash the affected area with soap and water immediately to remove the oil and reduce the risk of defatting.
  • No Eating or Drinking. Never eat, drink, or smoke in areas where motor oil is being used or stored to prevent accidental ingestion.
  • Dispose Properly: Dispose of used motor oil responsibly by following local regulations and guidelines. Avoid pouring motor oil down drains or into the environment.
  • Seek Medical Attention. If you experience symptoms such as severe skin irritation, respiratory distress, nausea, vomiting, or aspiration, seek medical attention promptly.

Final Thoughts on Motor Oil Toxicity

Is motor oil toxic to humans and animals? Yes. That is why you should be careful when changing your motor oil and disposing of the substance. Although motor oil is crucial to the function of your vehicle, do not underestimate its ability to cause harm. Even a small mistake can harm you or the environment.

Categories: Oil Guides


Hi, I’m Alastair. Welcome to, a website for the best oil recommendations for your vehicle, whether it is a two-door sports car, SUV, hatchback, or tractor. Having grown up on a family farm and working as an engineer, I became interested in just about anything with an engine. I also found that motor oil, despite being essential for internal combustion engines, is overlooked, underestimated, or just misunderstood. There may come a day when motor oil is obsolete as electric vehicles become more and more popular. But until then, you are going to need to know the best type of motor oil for your vehicle. That is why I was inspired to create this website. aims to be the internet’s destination for everything related to motor oil, including news, comparisons, features, and recommendations for vehicles by make and model. All the information you need to keep your treasured vehicles running clean is right here. In particular, I am also obsessed with the upkeep of vehicles in general. That is why you will also find troubleshooting tips for removing oil filters and drain plugs, for example. Consider it the mission of to provide accurate information, as well as insight for automotive professionals and enthusiasts.


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