It’s oil good
Your rig – whether it’s a bakkie or SUV – is more than just a vehicle. It’s your travel companion, and you want to keep touring with it for as long as possible. The best way to keep it healthy? Use the right oil.
Engine oil plays a critical role in your vehicle’s engine: it forms a slippery layer on the metal surfaces of the engine, thus reducing friction and wear. Without oil, your vehicle’s engine will only run for a few minutes before seizing up – and the resulting damage will be bad. By adding oil and replacing it regularly, you can extend the life of an engine from a few minutes to several decades.
Good oil not only keeps friction to a minimum, but it also improves fuel economy, helps prevent degradation and rust that would otherwise damage parts, and it cools the engine by conducting away heat.
Two types of oil are available: synthetic and mineral oil. The latter is distilled crude oil (or processed coal) with various additives for better performance. Despite its name, synthetic oil is not entirely man-made but rather a natural oil base that’s been chemically altered in laboratory conditions, which is why it’s so expensive. Semi-synthetic oil must contain at least 10% synthetic oil according to the API standard (that is, the American Petroleum Institute) to be called as such.
The viscosity – or resistance to fluidity – of engine oil plays a significant role in how efficient it is. A liquid with high viscosity, such as hot tar, will be slow to lubricate your engine parts and will impede the free movement of pistons, ball bearings, and gears. On the other hand, a liquid with a low viscosity – diesel, for example – will not cling well to parts to help reduce wear. Good engine oil has the right viscosity to adhere to metal without affecting performance.
Modern synthetic oils form
thin layers that offer the same protection as cheaper mineral oil, but they allow higher revolutions. It’s also less likely to accumulate impurities such as microscopic metal filings and then circulate them through the engine. As we’ve already mentioned, synthetic oil is much more expensive than mineral oil, and it’s a decisive factor in a country like South Africa that’s reeling from rising – and rising some more – fuel prices.
Using synthetic oil is like being on a diet consisting of salmon with saffron and a salad. This diet is extremely healthy, but few of us can afford to eat salmon every day, never mind saffron.
Mineral oil, on the other hand, is more like eating meat and potatoes. It may not be the healthiest food on Earth, but it does the job.
Jacobus Langenhoven is a technical manager at TotalEnergies South Africa, and he knows everything there is to know about lubricants. According to him, choosing the right lubricant for your car can be like the difference between a bronze or a gold medal for an athlete.
“If you want to ensure your car is a tireless athlete, you need to look at its overall health. An athlete strives to be in optimal health, and they take care to ensure that their body receives the best sources of nutrition. But they’re also concerned with performance and using clean, efficient supplements and nutrients to go the distance,” says Jacobus.
“Many of us want to take better care of our vehicles, which is why a lot of people interested in cars will choose synthetic lubricants. But a semi-synthetic is also an option and can be a cost-effective compromise for end users.”
We wanted to know if a more expensive (and hopefully better) oil would save us money in the long run. Jacobus’ response was that the right oil for your vehicle will definitely extend the life of the engine. On top of that, he says, your maintenance costs are going to be lower and your repairs less.
Jacobus also believes that there are short-term benefits, such as better fuel consumption and higher performance. “Many lubricants have been designed to improve fuel economy, and this relates to the additives that can alter the viscosity of the lubricant, meaning it’s easier for your engine to function on less fuel. That’s one thing you can check for on the label of any bottle of lubricant.”
Here, Jacobus refers to not only the ingredients in the oil but also the viscosity grading; or the so-called SAE number.
Krystyna Buda-Ortins tested the auto-ignition point of several cooking oils for the Department of Engineering at the University of Maryland in the United States in 2010.
Sure, neither of the two academic papers deal with the use of cooking oil in car engines, but the findings still offer food for thought.
Diamante’s paper discussed an almighty 13 types of cooking oils, from avocado to walnut oil. However, we’re going to ignore exotic stuff like rapeseed and safflower oil and only discuss the results for sunflower, canola, olive, and avocado oil (the usual cooking oils you get at Checkers).
Diamante’s finding was that avocado oil has the best viscosity at an outside temperature of 26 °C with 0,0576 Pa·s (Pascal second, the unit by which the viscosity of a Newtonian liquid is measured). However, your rig’s engine gets much hotter than that – between 90 °C and 120 °C (oil in a sump is usually 10 °C cooler than at the top of an engine) – which is why we took the results for Diamante’s viscosity test at 90 °C. The winner here is canola oil at 0.0108 Pa·s.
We consulted Buda-Ortins’ paper on the risk of the oil spontaneously combusting. She determined that olive oil starts smoking at 130 °C (canola oil smokes at 154 °C), but that olive oil lasts the longest and only bursts into flames at 435,5 °C. Unfortunately, Buda-Ortins did not mention whether it was extra virgin or regular olive oil.
However, your vehicle’s engine should never reach this extreme temperature, and if you use cooking oil as engine oil, it will probably not even smoke excessively, although the smell of the exhaust gases may remind you of a fish and chips shop.
But how does cooking oil compare to engine oil in terms of viscosity? According to the Anton Paar oil laboratory, the viscosity of cheap SAE 30 oil (for your lawnmower) is 0,0114 Pa·s at 90 °C. In contrast, the figure for full synthetic SAE 10W-60 at the same temperature is 0,0243 Pa·s. Canola oil is – when it comes down to the numbers – poorer than even the worst motor oil, but not as bad as you’d expect…
Note that Diamante and Buda-Ortins’ academic papers consist of thousands of words and contain complex formulas and rheogrammes, a kind of diagram that depicts shear stress versus shear rate – and here we’re trying to explain it in layman’s terms in just a few hundred words. Also note that engine-oil manufacturers conduct comprehensive tests to develop the best lubricants. We’re therefore not saying that you should be pouring regular cooking oil into your engine. On the contrary, we strongly discourage you from doing so.
Our reasoning, though, is as follows: when you’re stranded in the middle of nowhere and there’s only a small chance that someone will come accross you, you have one of three choices. You can wait for better days; you can drive without oil and see how far you get; or you can consider cooking oil – provided you packed 5 ℓ of it – because even bad oil is better than no oil at all. Just don’t rev the engine excessively and drain the cooking oil as soon as you can and replace it with real motor oil.
We’re therefore not saying that you should be pouring regular cooking oil into your engine. On the contrary, we strongly discourage you from doing so