Far more than just a lubricant, modern motor oils are very complex blends that are vital to the overall health of an internal combustion engine. To find out more, we spoke to LIQUI MOLY’S Oliver Kuhn, as he explains just why this versatile fluid is so precious and needs to be considered with utmost care.
Q. WHAT DOES ENGINE OIL DO?
A. Although the main task of engine oil is to lubricate things, it also has many more jobs: it cools the engine components; it removes deposits and transports them to the oil filter; it seals the piston rings; and it protects the metal surfaces from corrosion.
Q. WHAT DO THE DIFFERENT GRADES OF OIL MEAN?
A. There are many different grades of oil available, and the most common measure to differentiate them still is the viscosity (e.g. 5W-30). However, this is a little outdated these days. In the past, viscosity was the defining factor to keep different oils apart, but today the world of oils has become far more complex, and viscosity is just one of many factors to consider. More important in modern engines, are the specifications issued by associations such as API, ACEA, and ILSAC, or by the manufacturers themselves.
Q. WHY ARE THERE DIFFERENT SPECIFIC MANUFACTURER GRADES OF OIL?
A. Because different manufacturers follow slightly different approaches to engine technology; this results in different requirements for the engine oil. It’s best to think of modern engine oils as spare parts designed to fit specific applications, rather than as general lubricants.
A modern engine needs an oil that precisely meets a strict set of requirements. Pouring in the wrong oil is like installing an incorrect replacement part. The crucial difference here is that there is a safety net when trying to fit the wrong physical parts – they just won’t fit. However, when you pour in the wrong oil you won’t notice immediately, so you need to be sure you’ve got a suitable product before you install it.
Q. ARE ALL ENGINE OILS THE SAME?
A. Are all cars the same? Of course not. The same applies to engine oils. There are many similarities but there are also many differences. The most obvious one is the different viscosities. Then there are the different ingredients: mineral or synthetic base oils, plus the many different additive packages. Their combination leads to a multitude of different oil properties, adapted to the individual requirements of the different engine technologies. Therefore, you need a specific oil to suit a specific engine.
Q. WHAT’S IN AN ENGINE OIL?
A. Engine oil consists of two main ingredients: base oils, and the additive packages. Base oils are what you would typically describe as the actual ‘oil’. There are many different types of base oil, but the true performance of a modern engine oil comes from the additive packages. It is these that protect the engine from wear, keep it clean, protect from corrosion, suppress foaming, and define the viscosity range.
These additive packages make up to 30 per cent of the total oil volume and are crucial for the engine oil. Without the additive packages, an engine running plain base oil would suffer severe damage after just a few miles.
Q. WHAT’S THE DIFFERENCE BETWEEN MINERAL AND SYNTHETIC OILS?
A. Mineral oil is the traditional type of oil that’s refined from crude oil; it’s cheap, but it’s made up of various different chemicals. This reduces the performance of the oil itself, as well as the performance of the additive packages too.
Synthetic oils, on the other hand, offer much better performance. This is because they are not simply refined from crude oil, but are newly created on a molecular base. Synthetic base oils don’t look like traditional oils (they are clear), and they don’t have that distinctive oily smell either – in fact, they don’t really smell of anything. Almost all new motor oils for cars are made from a synthetic base oil, purely because mineral oils cannot deliver the required performance.
Q. HOW DO QUALITY OILS DIFFER FROM CHEAPER ONES?
A. In term of performance and quality. Premium oils can be used for extended oil change intervals if the car manufacturer allows this – typically this doubles the oil change interval without compromising the engine.
Quality oils, like the ones from LIQUI MOLY, are usually approved by the respective car manufacturers; it’s not just us saying the oil meets certain specifications, but the manufacturer has tested and officially approved it for use in their engines too.
Q. I’VE TUNED MY ENGINE, SHOULD I USE A DIFFERENT OIL?
A. This depends on how much you’ve modified things in the engine. Usually, it’s not necessary to change the oil technology, and you are well advised to adhere to the manufacturer’s instructions. If the manufacturer’s specifications allow for multiple viscosity grades, you may want to pick the higher one.
Great choices for tuned engines are our Leichtlauf High Tech 5W-40 for older engines, and our Top Tec 4110 5W-40 for newer engines. Both oils cover a wide range of specifications.
However, if the modifications have changed things significantly from the factory specs, then a different oil may make more sense – your engine builder will be able to advise.
Q. CAN A DIFFERENT OIL REALLY GAIN ME EXTRA HORSEPOWER?
A. An oil can’t physically gain you any power, but it can certainly help you lose less through frictional losses. Using oil with special wear protection – like our Molygen series – reduces the friction so the engine consumes less power; resulting in more of it being translated to the road.
Q. WHAT CAN I DO TO KEEP MY OIL IN GOOD HEALTH?
A. The worst thing for engine oil is doing lots of short-distance trips: cold starts mean increased wear; unburnt fuel gets into the oil; and the oil never reaches its operating temperature, so the fuel in the oil does not evaporate and the problem continues to get worse.
In fact, this puts a greater stress on the oil than racing on a track does. So, if you drive lots of short-distance trips, take your car for a longer drive every now and then.
Also, when you change oil it’s a good idea to clean the system with LIQUI MOLY Motor Clean first; this quickly and effectively dissolves deposits in the oil cycle, which then are drained together with the used oil. The fresh oil gets into a clean system and can deliver its full performance.