Fast Car

ENGINE OILS

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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 However, this is a little outdated these days.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.

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