Using Vegetable Oil as Engine Oil Replacement

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Will cooking oil (palm or vegetable) serve as engine oil? Turns out you don’t need to try – there has been a lot of research in the field already

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To say I was shocked is an understatement…this was a bike with an expressly recommended engine oil weight and here was this fellow, pouring not just any weight of engine oil but plain, good old cooking palm oil into its crankcase!

Now, as I registered extreme shock and turned away in disgust, the algorithms of the platform I was on noticed me – and recommended yet another palm oil to engine oil-inspired video.

This time, it was a vehicle, the Nissan Murano, and the owner confidently stated that he had been using palm oil instead of engine oil for a long time and that, all had remained well with his car.

At this point, I started doubting all that I knew and had been taught: this man was either lying or my knowledge of the ICE was faulty – so I decided to dig deep to find out which it was.

The results shocked me to my marrow.

Using Vegetable Oil as Engine Oil

As it turns out, I wasn’t the first person to be interested in this field; many folks had published research papers detailing all that I needed to know and make an informed decision.

And, these were no ordinary papers: they were research works of seasoned academics who knew what they were doing and had only reported what they found out from actual research.

Long story short: vegetable oil (palm and coconut oil) is better than conventional mineral oils which are non-biodegradable and prone to environmental pollution (source, PDF).

But, it just did not end there: there are several reasons why vegetable oil offers a better alternative to traditional, petroleum sourced based oils,

5 Reasons Why Vegetable Oil Beats Mineral Oil as Engine Lubricant

There are several reasons why vegetable oil trumps traditional mineral-based oil for engine lubrication. These reasons are:

1. Better fuel efficiency.
2. Cheap and renewable nature of vegetable oil when compared to mineral-based options.
3. Higher flash/fire points.
4. Higher boiling points.
5. Lower volatility, rapid biodegradation, and better skin compatibility.

1. Better Fuel Efficiency

Times are crazy now and gasoline isn’t the cheapest thing available at the moment. It thus makes sense to draw the last mile from every gallon of gasoline you put in the tank.

This is where vegetable oil beats conventional engine oil as a lubricant for internal combustion engines.

Mannekote and Kailas (2011),¹ using a four-stroke engine for this test, determined that the higher lubricity of vegetable oil when compared to conventional engine oil blend offered lower friction losses and as a result facilitated better fuel economy when in internal combustion engines.

In their words:

“…the neat vegetable oil without additives was better in comparison to the fully formulated standard mineral oil based lubricant…”

This came to me as a surprise, especially since this test used ‘raw’ vegetable oil, unmixed, unblended.

2. Cheap and Renewable Nature of Vegetable Oil When Compared to Mineral-Based Options

Crude oil – the primary raw material for the manufacture of mineral-based engine oil is a finite resource.

What this means is simple: even for naturally blessed countries like Nigeria, in less than fifty years from now, if no new oil reserve discoveries have been made, the last crude will have become extinct!

The implications of this are better imagined than lived: mineral oil isn’t simply sustainable.

Vegetable oil, on the other hand, is obtained from renewable plant sources – and can always be planted or grown.

Not only is it clean and infinite, but it’s also comparatively, cheaper.

As Basha, et al noted: “Vegetable oils as lubricants provide a new renewable source of environmentally friendly and economically better compared to commercially available lubricants in the market…”

3. Higher Flash/Fire Points

According to Basha, et al, already quoted above, the flash point of a compound “…is (the) auto-ignition temperature at which a particular organic compound gives off sufficient vapor to ignite in air.”

For fire point, the authors had this to say: “For fire point detection, the sample continues to be heated until permanent flame is detected which is known as fire point…”

For a lubricant, it makes perfect sense, without any further demonstration, that its flash/fire points are as far off as possible.

Unfortunately, base mineral oil, derived from petroleum does not present impressive figures in this regard. Cooking Oil, consistently, beats it to the game as the table below shows:

4. Higher Boiling Point

Closely related to the flash and Fire points is the boiling point which is “the temperature at which the vapor pressure of the substance is equal to the pressure surrounding the substance, causing the substance to change from a liquid to a gas.”

A good lubricant, according to Ojaomo, et al (2023), has the following characteristics: high boiling point, high viscosity index, prevention of corrosion, low freezing point, thermal stability, and high oxidation resistance.

The high boiling point is the most important – given that its failure means certain overheating and importantly, failure of the fluid as a lubricant.

In addition, besides vegetable oil having a higher Boiling point when compared to conventional engine oil derived from crude oil, it also ensures less emissions, while doing its thing in the crankcase of the test internal combustion engines.

5. Lower Volatility, Rapid Biodegradation, and Better Skin Compatibility

To wrap up the various benefits of vegetable oil over conventional engine oil as automobile engine lubricant (PDF), it’s important to note that vegetable oil has lower volatility overall, when compared to traditional engine oil. This results in an overall decrease in exhaust emissions and a cleaner air/society.

In addition, vegetable oil degrades rapidly (it’s edible, by the way) – which further reduces environmental hazards to the barest minimum, ensuring a safer earth for all.

Finally, vegetable oil as represented by both palm and coconut oil offers better skin compatibility, ensuring overall higher cleanliness and less dermatological issues at the workplace.

The Interesting Caveat

While the argument for vegetable oil has been strong, persuasive, and convincing, none of the research I came about expressly mentioned light synthetic engine oil formations, which are known to be more fuel efficient, lighter, etc than the traditional options used here.

It would have been interesting, to take a look at the Mobile 1’s 0W20 or 5W30 full synthetic, for instance…and compare the same with vegetable oil….

Wrapping up the Vegetable Oil vs Engine Oil Debate: Should You Switch to Cheaper Cooking Oil?

Of the research quoted here, it’s instructive to note that none of it conducted tests to confirm the superiority of vegetable oil over light, synthetic engine oil.

It’s also instructive to note that in most of the research listed above, vegetable oil wasn’t used in its raw form, as a pure base; rather, ‘blends’ (additives) were added to cooking oil in increments of 25%, unless otherwise stated.

My verdict?

Additives, as these authors argue (PDF), “…have three fundamental parts, they enhance existing base oil properties with antioxidants, corrosion inhibitors, anti-foam agents and demulsifying powers.”

These additives are what make cooking oil competitive with crude petroleum or if you prefer, mineral oil, when processed to engine oil.

As shown by Mannekote & Kailas (2011) already quoted above: “Ferrographic results have shown that the overall performance of these oils was comparable when tested under running conditions. When load is applied, the overall performance of engine oil was better when compared to coconut and palm oil.“

Summary?

Since you’ll need to actively ride your motorcycle or vehicle when you’re using vegetable oil in its crankcase (which amounts to putting load on the engine), traditional engine oil will still perform better overall than playing with palm or coconut oil – even if they somehow beat it regarding other points.

So, for now, if you cannot blend your lubricating oil using cooking oil as a base, best to stick with what your manufacturer expressly recommends, even if it happens to be more expensive than you’d like.

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Reference(s):

1. Mannekote, J. K., & Kailas, S. V. (2011). Experimental investigation of coconut and palm oils as lubricants in Four-Stroke engine. Tribology Online, 6(1), 76–82. https://doi.org/10.2474/trol.6.76 ↩︎