While many of us are stuck at home amid the ongoing national lockdown, our vehicles have sat stagnant for weeks, only making their way out for short trips. This got me thinking about engine oil, its importance and the different types of engine oil available.
For an engine, oil is as important as water is for our bodies, without it, we would not survive. It isn’t that simple though, oil doesn’t hydrate your V8 and provide it with electrolytes as water does with us. It instead provides a buffer, preventing metal-on-metal contact. Without oil to lubricate and cool moving parts, keep them clean and help to seal the pistons in the cylinders, the engine would run for a short period, then seize or destroy itself.
Different strokes for different…strokes
There are many different types of oil available for cars, SUVs and heavy-duty vehicles. Your vehicle owners’ manual does recommend what oil to use but that is under the assumption that the vehicle is new. Older vehicles have different oil requirements so let’s take a look at the different types of oil, but first, let’s tackle what those digits on your oil drum mean.
Those numbers and letters
Let’s, for argument sake, your vehicle’s recommended oil is 5W-30, what on earth does that mean? Let’s start with the ‘W’ which stands for ‘Winter’. The digits listed are the viscosity rating of the oil determined by the Society of Automotive Engineers (SAE). The number before the ‘W’ represents the viscosity of the oil when cold and the digit after the ‘W” represents the oil’s viscosity at normal operating temperature. The lower the number, the thinner the oil and the better it works in cold conditions and the higher the number after the ‘W’ the better the oil operates at high temperatures.
Types of oil
Mineral oil- As its name suggests, mineral oil consists of oil that has been extracted from the earth and refined with additives, to be used in your vehicle’s engine. Mineral oil is a popular choice because it is relatively cheap and is what older vehicles have been running on for years. The problem is that this oil tends to break down (oxidise) sooner and struggles to handle high temperatures as a result. It is also known to be quite thick and contain certain impurities.
Semi-synthetic oil- Semi-synthetic oils are also popular because they are affordable, as the name suggests, these oils combine mineral oil as well as synthesised oil and can tolerate changing temperatures better. This generally means they’re less volatile, so they evaporate far less, which reduces oil loss (and improves fuel economy). They’re popular with drivers of bakkies and SUVs who want the high-load protection. They’re a lot less expensive than full synthetics, maybe just pennies more than a premium, conventional oil.
Fully synthetic oil- This oil is man-made and therefore formulated to provide the optimal protection and performance for your engine. It certainly costs more however many modern engines, especially now with turbocharging, require an oil that can withstand head. If these oils pass stringent tests (indicated by their labelling), it means they have superior, longer-lasting performance in all the critical areas, from viscosity index to protection against deposits. They flow better at low temperatures and maintain peak lubricating function at high temperatures. So why shouldn’t everyone use them? Well, these oils are expensive and not every engine needs them. There may be some features that your car’s engine needs that the synthetics don’t have. Again, follow your owner’s manual or consult a mechanic.
Higher Mileage Oil: Not all of us can afford new cars, some of us keep our cars for a long time and others love the idea of owning a classic. If you own or want to own a high mileage car, you have another oil choice, those formulated for higher-mileage vehicles. There are many cars on the road which have more than 150 000km on the clock. So the oil makers have identified this as an area of customer interest, and have specially designed oils they’re recommending for these vehicles.
Why does my older car require special treatment?
When your car is somewhat older and has considerably more mileage, you may notice a few oil stains on the garage floor. It’s about this time that you need to add a quart more often than when the vehicle was new. Crankshaft seals may have hardened and lost their flexibility, so they leak (particularly at low temperatures) and may crack. The higher-mileage oils are formulated with seal conditioners that flow into the pores of the seals to restore their shape and increase their flexibility which reduces the risk of a leak.
You may have noticed some loss in performance and engine smoothness as a result of engine wear on your higher-mileage vehicle. These higher-mileage oils also have somewhat higher viscosities. They also may have more viscosity index improvers in them. The result is that they seal the piston-to-cylinder clearances better, and won’t squeeze out as readily from the larger engine bearing clearances. They also may have a higher dose of anti-wear additives to try to slow the wear process.
