Alternative fuels and hybrid drives are on the increase to promote eco-friendly mobility. Using special test methods, MANN+HUMMEL is developing fully synthetic oil media with an excellent filtration performance for the special requirements of these technologies.

A functioning oil circuit is essential for a combustion engine. The condition for frictionless performance is the oil purity which is ensured through oil filter systems designed for the application. The trend to eco-friendly mobility and the associated spread of new fuels, improved drives and alternative drives also requires a rethink when it comes to oil filter media.

Compact and robust

The use of alternative fuels, for example, may mean that conventional filter media made from cellulose or mixed fiber media with cellulose and synthetic fibers quickly reach their limits. One reason for this are complex chemical interactions between the components of the fuel and its combustion products which mix with the oil and additionally accelerate the ageing process of the filter media. The strength of the filter medium suffers as a result and in extreme cases can tear. In terms of resistance to ageing, synthetic filter media are far superior to conventional media.

They also have one further advantage: With the structure of a synthetic filter medium, the differential pressure of a synthetic filter element is greatly reduced compared to a conventional filter element. This reduces the need to open the bypass valve and sometimes makes it unnecessary altogether. The bypass valve, for example, protects the filter element during a cold start from a higher load by opening. As a result, the pressure on the medium decreases. However, in that moment unfiltered oil flows to the clean side. In particular with cold start phases, which can be frequent with hybrid vehicles, the lower differential pressure of synthetic filter media proves to be advantageous. Due to the fact that a lower differential pressure is also the condition for a compact filter size, synthetic media also offer excellent potential to reduce the size of the filter.

Waterproof and dimensionally stable

The combustion of compressed natural gas (CNG) or fuels containing ethanol generates more water. This attaches itself to the blowby gas in the crankcase and subsequently enters the engine oil. Especially for short journeys when the engine has not heated up enough to vaporize the water, the water component in the oil can reach 5 percent. The water softens up cellulose-based filter media which in turn leads to a substantial increase in the differential pressure of the filter element. The consequence is a deformation of the pleats which can be permanent and impair performance. These problems do not occur when synthetic media is used.

Up to now, there have been no tests included in the standard specification of oil filters which are able to recognize problems caused by water in the oil. Customers also seldom specify the differential pressure requirements in the low temperature range, even though at low temperatures the differential pressure is at its highest. MANN+HUMMEL has therefore developed special laboratory tests to examine the influence of water on oil and also for critical temperature ranges. Together with customers, MANN+HUMMEL conducts tests in cold chambers, cold climates and short-haul operations, where it is possible to measure the direct influence of temperature and water on the oil filter.


In the new g‑tron series from Audi, fully synthetic oil filter media from MANN+HUMMEL are able to fully exploit their advantages. The Audi g‑tron models can use fossil natural gas, biomethane and the environmentally-friendly Audi e‑gas. This is a synthetic methane which is produced from electrolytically produced hydrogen and CO2 from the exhaust gas flow of a waste biogas plant. The Audi A4 g‑tron, for example, with its 2 liter EA888 Gen3. BZ petrol engine 125 kW (170 HP) designed for use with gas, is able to drive for 500 kilometers on one tank of gas and a further 450 kilometers with petrol operation.

And the development process in continuing. MANN+HUMMEL is already working on fully synthetic media for drives of the latest generation which will shortly enter series production. The basis for this is modern simulation technology and extensive expertise accumulated over many years.