API SM, API SN Plus | Engine Oils

Huge selection of motor oil from many manufacturers. You have the choice!

Among all lubricants and fuels in the car, engine oil is of particular importance. As the central link between mechanical friction and power generation, the engine oil plays a decisive role in the transmission of power from the engine in the car and is therefore exposed to various loads during each individual journey. If one considers that the intervals between oil changes are sometimes as short as 30,000 km, the importance of engine oil quality becomes even clearer.

Engine oils can essentially be distinguished by their viscosity, their manufacturer's approval or recommendation, and their basic chemical structure. Usually the viscosity is specified in an SAE class. In modern passenger cars, multi-grade engine oils are used which are capable of exhibiting different viscosities in the cold state, such as when the vehicle is cold-started, and in the warm state, i.e. at regular operating temperature up to the maximum load. This is a significant advantage, as an engine oil is thus able to ensure the rapid lubrication of an engine during a cold start with the highest possible flowability, thus guaranteeing qualitative aggregate protection, while at the same time offering a higher viscosity at high operating temperatures in order to be able to maintain a reliable lubricating film under heavy loads. Widely used viscosity grades in cars are SAE 0W-30, 5W-30 and 5W-40, which have replaced the once dominant viscosity 10W-40. An engine oil with a viscosity of 0W-30 is more fluid in comparison to the 5W-30 engine oil when cold and is therefore able to oil the engine more quickly and build up a protective lubricating film more quickly. In addition to the viscosity, automobile manufacturers limit the quality requirements for an engine oil to be used more precisely by specifications or so-called manufacturer's approvals. Common specifications are defined by the manufacturer-independent institutions ACEA (Association des Constructeurs Européens d'Automobiles), the API (American Petroleum Institute) or the ILSAC (International Lubricants Standardization and Approval Committee). Lubricant manufacturers can produce their products according to the classes defined in each case, such as ACEA A3/B4, API SN or ILSAC GF-5, while automotive manufacturers define which specifications must be met for the various vehicles. By specifying an engine oil specification, it is possible to identify in particular whether an engine oil is suitable only for petrol engines or also for vehicles with diesel engines. In the case of requirements for a lubricant individually defined by the vehicle manufacturer, a standardised specification is replaced by the so-called manufacturer approval or operating instructions. An approval is issued directly by the vehicle manufacturer. Oil manufacturers use it to produce products that meet the technical requirements of such an approval. Some of these products are then licensed and officially approved by the car manufacturer (in our online shop, the approvals of an engine oil  are listed in the product details under "approvals:") or recommended by the lubricant manufacturer as being suitable for use in vehicles that require an engine oil of the respective operating regulation (in our online shop, these are delimited from the manufacturer releases as "recommendations"). The most popular operating regulations defined by the automobile manufacturers include BMW Longlife-01, Mercedes-Benz MB 229.52, VW 505 00 and 507 00 or GM dexos2. However, there are also various other approvals from the vehicle manufacturers BMW, Mercedes, VW, Ford, Chrysler and many others.

In ATO24's online shop, you will find products from well-known lubricant manufacturers as well as a wide range of OEM products with which car manufacturers sell lubricants under their own brand. Due to our wide range of products we are able to provide the right motor oil for almost every vehicle - at a reasonable price and with short delivery time, no matter if European, American, Asian vehicle, passenger car, SUV, sports car or super sports car.

API SN Plus Oil vs. LSPI

"Smaller" (downsized) engines with turbochargers and direct injection are widely used nowadays. After all, they make it possible to reduce CO2 emissions. At first glance, this sounds very good, but it has one drawback - the problem of Low Speed Pre-Ignition, or LSPI for short.

LSPI describes the combustion of the fuel-air mixture in the combustion chamber of an engine that takes place before the actual combustion initiated by ignition sparks. This can lead to excessive pressure in the cylinder and, in the worst case, cause serious damage to the engine.

Low Speed Pre-Ignition presents the automotive industry with a major dilemma - on the one hand, they want to meet the ever-growing demand for fuel-efficient vehicles, but on the other hand, the engines specially designed for this purpose are susceptible to LSPI.

What to do against LSPI?

Research on LSPI shows that, among other things, the formulation of the engine oil plays an important role in solving the LSPI problem. For this reason, calls from the automotive industry for engine oils that can counteract the problem of LSPI have been growing.

Now, the American Petroleum Institute (API) has responded to these demands with the API SN Plus specification.

What does API SN Plus mean?

Strictly speaking, the API SN Plus specification is not a completely new engine oil specification, but an addition to the existing API SN and ILSAC GF-5 specifications. API SN Plus has been valid since May 2018 and was developed specifically for "downsized" engines with exhaust gas turbochargers and direct injection systems, which require an engine oil with the API SN specification, in order to counteract the problem of Low Speed Pre-Ignition (LSPI) and to protect vehicles or the engines from LSPI.

As mentioned earlier, API SN + is the most current specification of the API classifications created by the American Petroleum Institute. The API classifications distinguish between gasoline and diesel classifications, which are identified either by the letter "S" for Service or Spark Ignition for gasoline engines and by the letter "C" for Commercial or Compression Ignition for diesel engines. This is followed by another letter that reflects the quality level - the higher the letter, the more demanding the test for the oil.

What is the difference between API SN and API SN Plus?

API SN + essentially corresponds to the API SN specification, but is supplemented by an additional test against LSPI (API Sequence IX Test). This can be seen very well in the following graphic: API SN is marked with the yellow line, while API SN Plus is marked with the red line. The values that must be achieved in the individual tests or sequences in order to obtain the API SN license are identical to the values that are required for the API SN Plus license. As a result, the two lines are mostly on top of each other, which makes the line orange. The only difference between the two specifications is the test against LSPI (API Seq. IX), which only applies to API SN Plus.

API SN Plus is backwards compatible with API SN, which means that engines that require an engine oil with the API SN specification can also use an engine oil with the API SN Plus specification.

API SN+ for which cars?

All cars that have a small (downsized) engine with turbocharger and direct injection technology have a higher LSPI risk. To a large extent, downsized engines are engines with three cylinders and a total displacement between 1.0 to 1.5 L.

If an engine of this type requires an engine oil with the specification API SN, then it is recommended to resort to an engine oil with the specification API SN +, due to the backward compatibility with API SN, in order to prevent potential low speed pre-ignition and protect the engine from LSPI. The vehicle owner's manual can be used to determine if an engine oil with the API SN specification is needed.

API SN Plus and GM dexos

API SN Plus, along with the GM dexos 1 Gen. 2 release, is the first step in the fight against LSPI. At the end of 2019 / beginning of 2020, the ILSAC GF-6 specification is expected to put even more focus on protection against LSPI.