People often ask us: does engine oil kill grass? We have heard that engine oil kills weed and trees. Some people also say that it acts as a good fertilizer. Weird, isn’t it?

Generally, engine oil is toxic to humans, marine life, and the environment, especially when you use used engine oil. Along with heavy metals that make up engine oil, it also picks up contaminants from the vehicle’s engine, making itself more toxic. 

We didn’t believe that engine oil is an effective grass or weed killer until we tried it ourselves, and we can’t wait to share the results with you. 

Engine Oil as a Fertilizer

Many people believe that the engine oil world is a good fertilizer, so we decided to research it.  Wherever we spray the motor oil, everything that comes in its way dies, whether they were weeds, flowers, or grass.

Not only this, we learned that in addition to killing plants, motor oil does not allow the land to grow more plants the following several years. 

Motor oil is a poison not only to your lawn but to the environment, marine life, and human life, so it’s better not to spray it on anything. 

Will Engine Oil Kill Grass?

Once you spill engine oil on the ground, it will end up contaminating and killing everything that comes in its way, including grass. Engine oil is sticky, insoluble, and can take up to years to degrade.  

Grass absorbs heavy metals and contaminants in the engine oil, killing itself and making the land infertile. If you want to kill grass, you can try other environmentally friendly methods. 

Using engine oil to do so is illegal and really harmful to the environment. Also, it can make soil permanently infertile. 

Environmental Friendly Methods to Kill Grass

If you are looking for cheap and effective methods to get rid of grass, do stick around. 

  1. Commercial herbicides are the most effective and fast method but may harm the environment. Before using, make sure to wear protective equipment to avoid irritation and burns. 
  2. The simplest and cheapest method is to put boiling water on the grass. However, it may consume a lot of time to apply this method if the lawn is big.  
  3. Spray vinegar on the grass. It is a natural and cheap method to do so. However, before doing so, check the weather forecast for any rain. If it rains, vinegar will wash off. 
  4. Stop watering your lawn. When grass dies and turns brown, you can pull it off with a shovel. 
  5. You can also use salt to kill grass on your lawn. Sprinkle salt all over the yard. Else, you can make a salt and water solution and spray it all over the grass. 

Make sure not to spray it on the plants you need as it will kill them too. Also, this method may take more time to perform the task. 

  1. For larger lawns, you can use the solarization method. Cover the grass with black plastic and hold it down with stones at each side and corner. The sun will burn down the grass. It may take up to two months to completely kill the grass. 

You can also use clear plastic, but we recommend using black. Black surfaces are a good absorber of light, thus will perform the task faster. 

  1. You can also cover the grass with wet cardboard or layers of newspapers. However, it may take up to several months to completely destroy the grass. This method comes with an advantage, once grass dies, the soil beneath will become nutrient-rich. 

Will Engine Oil Kill Weed?

Are you tired of weed growing in your garden? Because same. Weed killers are surprisingly expensive, and pulling them by hand requires a lot of labor. We have heard people suggesting killing weed with engine oil, so we decided to give it a try. 

Fortunately, wherever we sprayed the motor oil, the plants, weed, and grass died. Here is how you can kill weed too:

  • Carefully put engine oil into the sprayer.
  • Cover all the plants with plastic except weed, so motor oil does not destroy other plants.

Note: use clear plastic so the plants keep getting sunlight

  • Spray once on every weed. This amount will be enough to kill the weed effectively. 
  • Within 2-3 days after spraying, all the weed will disappear. 

Despite its effectiveness, we don’t recommend you to go for it because even a small amount of engine oil can destroy a million gallons of fresh water and make the soil infertile for ages. 

Environmental Friendly Methods to Kill Weed

Along with the methods mentioned above, you can also kill weeds with a lawnmower by spraying corn by-products, vodka, soap, covering them with mulch, or using a weed torch on them. 

If weed is growing in cracks and patios, sprinkle baking soda in cracks or seal the cracks with cement. 

Engine Oil Toxicity and Environmental Issues

Contains heavy metals like chromium, lead zinc barium, and polyaromatic hydrocarbons. It picks up contaminants from vehicles’ engines, making itself more toxic. In turn, it causes sewage problems, infertile soil, and water and land pollution.

Engine oil plays a significant role in contaminating the soil. This is why disposing of engine oil is illegal, and it can make the land infertile forever. 

Apart from this, engine oil is a water pollutant too. One liter of engine oil can contaminate one million liters of fresh water. Besides, engine oil causes eczema and skin cancer. Even if you just inhale it, it may end up creating severe health issues.  

How to Clean Up Engine Oil in Your Lawn

Have you accidentally spilled engine oil in your lawn and now worry that it will make your lawn’s soil infertile? Well, we have got your back. Follow the guide below to efficiently clean engine oil in your yard:

  1. Use a shovel to take out around 5 inches of contaminated soil carefully. 
  2. Put the contaminated soil in a bag and properly dispose of it. 
  3. Replace the dig-out portion with fresh soil and reseed anything you want. 

Does engine oil kill termite? Read our guide

FAQs About Does Engine Oil Kill Grass?

Do you still have questions? We have compiled frequently asked questions to help you out.

Does Motor Oil Stop Plant Growth?

Yes, it does. Researchers conducted a study to check the effects of engine oil on plants and leaf growth. They then concluded that the plant’s height decreased with the increasing quantity of motor oil added. 

In addition to this, the leaves on the plants also reduced, and the average leaf area decreased. Engine oil as less as a few milliliters can significantly affect plants and food safety, so it is better to keep engine oil away from your plants.

Does Engine Oil Kill Tree Stumps?

Yes, it does. However, there is a proper way to do so. First, you need to cut the tree to its stump. Now, drill holes in the stump and paint motor oil on it. As the tree’s living part is caked with toxic motor oil, the stump eventually dies out.

This is a cost-effective way to kill tree stumps. Overall, it is considered a successful method but is very harmful to the environment. The deeper the oil penetrates, the more harm it causes to the soil.

How Long Does Soil Take to Decompose Engine Oil?

Around 25 years. Engine oil is insoluble and takes a long time to decompose. This is why environmentalists ask you not to dispose of it in the ground. There are special precautions and guidelines to dispose of engine oil properly

That’s All

Now when someone asks you if engine oil kills grass, you have the answer. It may be an effective weed and grass killer, but you should never use it. The harm it brings is far greater than the minor advantage it is giving by killing grass and weeds. 

Engine oil is a harmful waste. As a responsible citizen, you must dispose of the engine oil appropriately, protecting millions of liters of fresh water, marine and human life, and soil contamination too.
If you want to use engine oil for other purposes such as painting wood, make sure to cover the ground with newspaper first.