Yes, the compatibility of engine oils must be ensured to allow a top-up at any time. However, you should note that a switch from mineral to synthetic and vice versa will change the quality of the original product. This means that the oil drain intervals will have to be adapted accordingly.
This ultimately depends on the vehicle manufacturer. In recent years, almost all German vehicle manufacturers have introduced longlife engine oils with extended drain intervals. It should, however, be noted that these oils will not lead to extended drain intervals in all engines. Here, your authorized auto repair shop is the best address to contact for advice.
Viscosity is a measure for the thickness or the thinness of a fluid. High-viscosity fluids are thick and flow sluggishly while low-viscosity fluids are thin and flow freely. High-viscosity oils therefore form thicker lubricant films, providing reliable wear protection for gears and bearings. Low viscosities – especially with engine oil – mean reduced splash losses and hence, improved efficiency and reduced fuel consumption. In manual transmissions, the shift forces increase with increasing viscosity, resulting in reduced operational comfort.
Base oils impart basic specific properties to the lubricant which are reflected in the performance of the finished products.
Mineral oils: Hydrocarbon compounds of different shape, structure, type and size (VI: 80-95)
Hydrocracked oils: Refined mineral oils with a higher purity level and an improved molecular structure (VI: 130-140)
Polyalphaolefins (PAOs): Petrochemical synthesis products – chemically synthesized straight-line hydrocarbon compounds (VI: 130-145)
Synthetic esters: Chemically synthesized compounds of organic acids and alcohols consisting of molecules of a defined shape, structure, type and size. (VI: 140-180)
Additives are insoluble compounds and/or active ingredients which are added to the above base oils. They change or improve the lubricant properties through chemical or physical action.
Chemically acting additives:
- Anti-wear additives
- Corrosion inhibitors
Physically acting additives:
- Viscosity Index (VI) improvers
- Anti-foam additives
- Pour point depressants
- Friction modifier
The SAE values designate the viscosity classes of motor vehicle lubricants as standardized by the Society of Automotive Engineers (SAE).
Example: SAE 0W typifies an extremely low-viscosity winter oil corresponding to the lowest viscosity class currently defined. By contrast, SAE 40 designates a high-viscosity summer oil. A multi-grade oil, e.g. SAE 0W-40 provides the same performance as SAE 0W in cold weather and the same performance as SAE 40 in hot weather. They cover the performance requirements for both cold starts at low temperatures and for driving on the motorway at high temperatures.
A low cold viscosity stands for quick engine lubrication during cold starts and hence reduced fuel consumption. A higher high-temperature viscosity stands for a reliable lubricant film at high oil temperatures but also for higher fuel consumption. With advanced engine oils there is a trend towards achieving optimum fuel economy.
When using high-quality base oils, a reduced high-temperature viscosity will also guaranteed a reliable lubricant film at all times.
An excess of oil in the engine is harmful for both the engine and the environment.
Too high an oil level may cause the engine oil to foam so that its lubricating function is impaired. At the same time increased amounts of oil mist will be carried over into the combustion chambers where they are not completely burned. Besides high oil consumption, unburned oil constituents will be entrained with the exhaust and enter the catalyst converter, where they deposit and will reduce the conversion efficiency in the long term. By routinely checking the engine oil, you can see when and how much to top up. In most engines, the difference between the MAX and MIN marks on the dipstick corresponds to roughly 1 litre. Therefore it is recommended to add 0.5 l at time when the oil level has dropped between medium and minimum.
As a matter of principle, the gas fuel system and engine manufacturers’ instructions should be observed. In the absence of engine oil information in the manual, we recommend a low-ash product as used in vehicles with diesel particle filter, for instance. The vehicle manufacturer approvals should, however, always be observed.
Small containers have a minimum shelf life of 5 years (when stored in a dry place at temperatures of between +5 and +30°C without direct exposure to solar radiation). Preferably, the oil should be stored in the basement of your house, for instance – rather than in the garage! Open cans should not be stored for longer than 6 months.