Everything You Should Know About Your Engine Oil
This is a topic that should be better covered in all driving schools worldwide. As a car owner, there are certain things you should familiarize yourself with. Being able to buy the correct engine oil is definitely one of those things. If you haven’t learned this information before, don’t worry, we got you covered. By the end of this article, you will learn why engine oil is so important, why choosing the correct engine oil is important and what are the differences between different engine oils. Let’s dive in!
Why does your car need engine oil?
The insides of your engine are always in motion. Those insides are made out of metal and in order to prevent mechanical friction, engine oil acts as a lubricant. Not only does it prevent mechanical friction, but it also cools the parts of the engine that get hot and which the coolant cant reach. On top of that, engine oil protects the engine against corrosion and cleans the engine of metallic abrasion, ash and soot.
Why do you have to change engine oil regularly?
Engine oil is working hard to prevent damage to your engine. By doing that it slowly degrades and loses its lubricating qualities. Other reasons for wear are natural oil ageing, the degradation of additives and viscosity index improvers and pollution from combustion residues such as soot, sulfur oxide, water and mechanical abrasion.
In order to prevent damage to your engine, just topping up or filtering your oil is not enough. Engine oil is not something you want to save money on, trust us. Do not forget about the oil filter as well. Each time you have an oil change, make sure you or the mechanic also replaces the oil filter.
The oil filter has the task of cleaning the engine oil from metal debris, dust and combustion residues before it reaches the lubrication points. For this purpose, the engine oil is sucked in from the oil sump of the oil pan by the oil pump while the engine is running and pressed through the oil filter with pressure.
How to choose the correct engine oil?
Different engines need different engine oils. This applies to gasoline and diesel engines, but also to different engine variants (don’t pour the two-stroke oil from your lawnmower into your car!). The engine oil needed for your car is chosen and prescribed by the car manufacturer for a reason. That is why there are many different specifications and oil variations such as BMW Longlife-04, Volkswagen 507.00 or Mercedes-Benz 228.51 for example.
Information on the prescribed engine oil classification can be found in the operating instructions or in the service booklet of your car. You can always ask your mechanic to provide you with the name of the correct engine oil for your car.
What does “5W-30” or “ACEA C3-12” mean in engine oil?
Those numbers you see on every engine oil packaging are describing the viscosity of the oil. Viscosity is a technical term for oil thickness or density. The higher the viscosity the thicker the oil is. When it comes to engine oils, viscosity plays a big part because of the fluctuating temperatures. During the winter, the oil should not be so viscous that it cannot be pumped into the engine quickly enough, and in the summer it should not be so thin that it loses its lubricating properties. This is why we have these “5W-30” numbers that represent SAE viscosity grades.
- The number in front of the “W” (5 in this case) stands for the viscosity of the oil at cold temperatures (W as in winter). The lower the number, the thinner the oil is at colder temperatures.
- The number after the “W” (30 in this case) describes the viscosity of the oil at the engine’s normal working temperature. The higher the number, the better lubricating properties remain, even at high temperatures.
Alongside SAE (Society of Automotive Engineers), you can also find ACEA specifications which are provided by the European automobile and mineral oil manufacturers. Here is how to read and understand ACEA specifications.
Example: ACEA “C3-12”
- Class A: for cars with gasoline engines
- Class B: for passenger cars and light commercial vehicles with diesel engines
- Class C: for gasoline and diesel engines with new exhaust gas after-treatment
- Class E: for commercial vehicles and trucks with diesel engines
systems (e.g. diesel particulate filters)
In the case of this example, the oil with “C3-12” is suitable for gasoline and diesel engines with exhaust after-treatment systems. The numbers after the “C” letter describe various oil properties and not just viscosity.
Mineral oil or synthetic oil – which is better?
Mineral oils are obtained from crude oil by distilling and refining and consist of many different hydrocarbon molecules. During the manufacturing process, the unusable components of the crude oil are eliminated. This process is relatively simple and comparatively inexpensive.
Synthetically produced motor oil is obtained from crude oil or natural gas. Here, however, the components are not “sorted out” but are specifically assembled in a chemical process so that the desired product is created. In this way, manufacturers can give the oil special properties – for example, particularly good lubricity at extremely low or high temperatures.
Synthetic oils are usually prescribed to high-performance and luxury cars but all cars can generally benefit from synthetic oil’s additives and capabilities. We recommend that you use whatever oil your car manufacturer recommends.
Frequently Asked Questions (FAQ)
There are several other questions we see get asked on a daily basis so we will try out best to cover them here.
What is “longlife oil” and can I use it to save money on oil changes?
Longlife oil consists of high-quality base oils and special additives. They tend to be thinner but with the use of special additives, still provide the necessary lubrication. Longlife oil is intended for vehicles with a long oil change interval specified by the manufacturer. In principle, only the oil quality specified by the vehicle manufacturer may be used on these cars – even when refilling. Do not use this kind of oil if your car is not designed for it!
What happens if you pour too much oil into the engine?
Having too much oil in the engine can cause engine damage. If you happen to just slightly over-fill your engine when topping up, we recommend you visit the nearest workshop for a quick drain. If you happen to exceed the maximum oil level significantly, we recommend you stop immediately and call roadside assistance.
How long can you store engine oil?
Oil manufacturers recommend storing closed oil containers for a maximum of 3-5 years. Opened oil containers should not be stored for more than 6 months.
My engine oil level is rising, what is happening?
If the oil level rises, it is usually due to oil dilution. This phenomenon occurs in diesel cars that are mainly driven over short distances. The cause: dust and soot collect and clog the diesel particulate filter. It has to be burned down again and again so that the filter does not clog.
Why do vehicles with a Diesel Particulate Filter (DPF) need special oil?
All engines burn a small amount of oil that eventually enters the exhaust systems. If your car has a DPF, those burnt up oil particles will flow through it. It is important that you use engine oil with low SAPS (sulfated ash, phosphorus and sulfur) so you don’t clog up the diesel particulate filter.
Can I change the engine oil on my own?
In modern cars, the oil drain plugs can often only be opened with special tools. Keep in mind that proper disposal of the old engine oil is also time-consuming. In addition, the oil drain plug is hardly accessible without a lifting platform or access ramp.
We only recommend doing it if you have had the proper training, are absolutely sure you know what you are doing and you have the tools and equipment to do it safely!