Is engine oil biodegradable?

There have been various tests in the recent past, which can help us either confirm or irrevocably deny the environmental repercussions of engine oil. Today, in this article, we study how fast does the engine oil biodegrade or decompose when discarded.

For the sake of the planet, we sure hope it does! With more and more people now being able to afford luxurious vehicles, engine oil is being used more than ever.

What is Biodegradability

To begin with, let us first understand what biodegradation really is. In layman’s terms, it is the ability of organic compounds to divulge into simpler compounds (water, methane, etc). This ability helps us keep the earth cleaner.

For instance, your paper would decompose and leave next to no footprints. However, plastic won’t go for some 200 years, and so, it is garbage we can’t get rid of.

The more biodegradability an item has, the lesser impact it has on the environment in the long haul. However, what makes items decompose, you may be wondering!

Microorganisms that are all around us! They feed off of everything, and in that process, they convert more complex substances into something lesser complex.

Intriguing, how even the smallest organisms have a huge role to play! Isn’t it? However, are they successful in decomposing engine oil?

Engine Oil’s Biodegradability

The soil contains bacteria that somewhat possess the ability of decomposing engine oil. Normally, the proportion of inorganic nutrients determines the biodegradability of your engine oil. You can process the engine oil to enhance the additives, which further makes them decompose at a much higher rate.

However, motor oil contains detergents, aspirants, and other toxic hydrocarbons. These will increase the chances of polluting the environment.

In such a scenario, the only choice left is treating the soil post the oil has been dumped, which is highly recommended against. Although soil treatment can be done using various methods, the oil does form strong compounds with soil’s minerals, and so, the damage is often beyond cure. Moreover, these methods to clean the ground can be very expensive and have limited efficiency.

So, it is evident: Engine Oil is not the most biodegradable lubricant!

What is a Biodegradable Lubricant

An oil that is high on decomposable organic compounds will be a biodegradable lubricant.

Motor/engine oil is, in order to improve its organic nature, combined with biodegradable bases. Vegetable oils and synthetic esters make for great organic compounds. Not only do they improve the engine oil with respect to its environmental footprints, but some of them can even replace the non-degradable additives used in the lubricant oils.

Nowadays, various guidelines have come about for the usage of biodegradable content while manufacturing lubricants. Oil, although not fully decomposable, is far better than grease.

Is Synthetic Engine Oil Biodegradable

The quantity of blended additives affects the biodegradability of your engine oil. Synthetic engine oil enhances the performance of your automobile engine. Moreover, it can be tailored to be more environmental-friendly, if we actively use synthetic esters in the process of its manufacturing.

Is Conventional Engine Oil Biodegradable

Conventional engine oil contains petroleum. Petroleum is faster at decomposition than most synthetic- based oils. It is not completely environment-friendly because conventional engine oil needs to be replaced and drained more frequently.

Engine oil Contaminating Environment

The problem with dumping engine oil into the soil is that it lacks nitrogen and phosphorous, which trigger decomposition. In some states, it is illegal to dump motor oil in the soil.

However, the processing of engine oil with nitrogen-rich nutrients (organic fertilizers) can enhance the biodegradation process. Petroleum decomposes at a faster rate in the soil. The biodegradation period of 10-40% of engine oil is approximately 12 months.

Higher concentration means a longer biodegradation period. After treatment, it can be, however, dumped into the ground. Dumping it into the water can lead to much bigger problems as we have understood what happens when there are petroleum and oil refinery spills in the ocean. Since no oil is soluble in water, it would float on the surface. This leads to a drop in the oxygen content under-water, which is needed to support the aquatic ecosystem.

So, here we have to choose the lesser evil, and that happens to be dumping in soil. However, we do not have to be careless about it, and with utmost caution and efficient factorization, we can reduce the damage it will cause.

How to Enhance Engine Oil Biodegradation

Lab experiments have proven to be very useful. We now know that using mushrooms and banana skin compost helps improve the decomposition of engine oil. Using organic fertilizers of the likes of cow dung manure, rotten green vegetables, etc, can further help. These are not just easy-to-do, but, they are also readily available organic products and don’t come with a giant price label.

Biodegradation Rate of Used Engine Oil

We have so far understood that the more an engine oil gets used, the more contaminants it has. Those toxic contents of that mixture will make it difficult for the microorganisms to decompose the engine oil.

Let us further examine the situation.

Figure 1 Biodegradation of engine oil in soil contaminated with 5% used oil mixed with 10% organic wastes.

BSG( Brewery Spent Grain), SMC (Spent Mushroom Compost), and BS (Banana Skin) are the various organic fertilizers used to fasten the process. In the graph above, we see that BSG has the highest decomposability.

Another interesting find is that the motor oil with 5% mineral oil base needs 84 days to biodegrade, and the degradation percentage is high, between 70-100%.

Figure 2 Biodegradation of engine oil in soil contaminated with 15% used oil mixed with 10% organic wastes.

Let’s talk about the biodegradation of 15% used engine oil. Now, here, the biodegradation rate is lower as compared to the 5% engine oil. No surprises here; the more your engine oil gets used, the more non-biodegradable inorganic its mixture gets! The biodegradation rate after 84 days is between 50% and 60%.

Microorganisms and Biodegradation Rate of Engine Oil

The presence of microorganisms in engine oil can also affect the decomposition rate. Depending upon the nature of these microorganisms, they may help break the toxic hydrocarbons or they may further enhance their chemical properties. Microorganisms also affect the solubility of the solution they are in. Not to forget, the dumping soil too has plentiful microorganisms in itself, which will, upon contact, react with the engine oil.

It is usually found that despite the microbial pigmentation, hydrocarbons just don’t break easily! Benzene, for instance, will take years in breaking. So, if we just dumped the engine oil into the ground, we are messing with the land’s fertility. Engine oil also contains PAHs (Poly Aromatic Hydrocarbons) that creates a strong bond with soil. This bond can damage the soil’s pH value, leaving it unfit for cultivation and fostering the animals that live underneath the ground, and this may contaminate our potable groundwater too.

This is why, if you are done using the engine oil, you have to contain it in an air-tight jar. Avoid exposing it openly, which can lead to microorganisms taking over the scene and making the situation far worse.

Final words – Is Engine Oil Biodegradable?

In conclusion, engine oil is biodegradable. However, the biodegradation rate may vary. Synthetic and conventional engine oil types have lower rates of biodegradation.

Moreover, the biodegradation percentage varies depending on how much has the subjected engine oil been used. It is visibly different for 5% used and 15% used engine oil types, as research indicates. Apparently, the lesser you use that engine oil, the more biodegradable it gets. The reason behind this higher biodegradation rate (with respect to more used engine oil) is the more your engine oil gets used, the more toxins and heavy metals dissolve in it, which reduces its biodegradability.

You can enhance the biodegradation rate of your engine oil using organic fertilizers. Usage of inorganic filters is detrimental to soil quality. Inorganic fertilizers react with the minerals found in the oil and create acidic compounds, which may ruin the composition of the soil they fall on.

It is important you dispose of engine oil properly. Leaving it out in the open can lead to fire hazards and unsupervised consumption, which can be fatal too. Recycling your engine oil is a far better option since used engine oil does not lack in quality still.

You should aim to make the most of the engine oil you use. Since it has environmental repercussions, we do not recommend swift oil changes. Although the newer variants of engine oil do not affect the environment so much, there is still a cost to pay!

You can inquire about the green rating of engine oil before you purchase it. We hope you make a judicious call for a greener and cleaner future.