Munich - Today’s vehicle engines no longer need frequent oil changes; intervals of up to 30,000 kilometres between changes are common. But as the service life of engine oil has lengthened, the requirements imposed on the lubricant have likewise become more complex. Many engines can only be operated using synthetic oils, and manufacturers’ specifications must be obeyed to the letter. The experts at TÜV SÜD have listed the ins and outs of modern oil usage.
Only a few years ago, viscosity was virtually the only engine oil characteristic that car drivers and garages needed to pay any attention to. The only question was whether a car needed 10W-30 or 15W-40 grade. High-quality oils were generally suitable for all types of engines. “Today things are trickier”, notes Eberhard Lang of TÜV SÜD. "Various categories – such as A5, B4 or C2 – must also be taken into account”. The situation is made more complicated by various changes and additions made to industry standards in recent years, adds Lang.
Filling up: TÜV SÜD recommends going to a specialist garage for oil changes, where the mechanics will know the correct oil type and can also leave a can or two in the car boot as a reserve. “Some highly specialised oil types are not automatically available at filling stations and auto supply stores – especially abroad”, warns Lang. Given the lengthy periods between oil changes, an engine top-up may well be required.
Checking out: The car’s manual is a reliable source of information as to which oil type is the right one. In addition, the websites of well-known oil brands offer assistance on choosing the correct oil for specific car models. Where highly specialised oils produced for individual car manufacturers are concerned, the packaging often provides the necessary information.
Viscosity: This characteristic indicates the thickness of the oil. Lower figures show the oil is thinner and flows more easily. Monograde oils with fixed viscosity are generally only used for vintage or classic cars; multigrade oils are more common. A category of 5W—40, for example, shows that the oil is extremely thin when the engine is cold (“5”) and increases to a viscosity level of 40 as the engine heats up. This is important to ensure the lubricant coating is maintained in the hot engine. The letter W indicates the oil is suitable for use in winter – a standard feature since the 1970s.
Synthetics: Many car manufacturers recommend using synthetic oil for modern cars; in fact, these oil types are actually mandatory for some cars, and many vehicle-specific standard oil requirements cannot be implemented with any other type. Only extremely old vehicles cannot take synthetic oils, which attack the material of the vehicles’ seals and gaskets. Users of mineral oils that decide to switch to synthetic oils should check their oil levels more frequently at first after changing over. “Synthetic oils can loosen up deposits, which may temporarily increase consumption”, advises the expert. In other cases the use of modern lubricants actually lowers oil consumption – which, incidentally, also extends to fuel.
Long life: Extremely long intervals between oil changes – 50,000 kilometres or more – need special long-life oils, which are relatively expensive. However, drivers should not be tempted to use a different type. “Today’s engines are often designed around a specific lubricant”, explains Eberhard Lang from TÜV SÜD. “The wrong oil not only results in poor exhaust values and reduces engine life – it may actually damage the engine.”
API, CCMC, ACEA: The oldest quality standards were drawn up by the American Petroleum Institute (API) and can still be found in many operating manuals. In addition to the viscosity category, they specify a combination of letters; the current highest quality level is SJ/CF. “With the exception of vintage and classic cars, the newest version of the API standard can always be used”, says Eberhard Lang. “The oils are downward-compatible.” In Europe the ACEA specification has now replaced the older CCMC standard. In addition to information about viscosity, it classifies oils into categories A, B and C. “These additional categories must be precisely observed”, warns Lang. They involve far more than an ascending measure of quality. “An A5 oil is not merely an improved version of an A3; it is completely different. Use of the incorrect oil results in failure of the lubricating coating and damage to the engine – which may extend to the diesel particulate filter.” Asian-produced vehicles often specify oils to JASO, JAMA or ILSAC standards; products are available with compatible European or US specifications. Some automotive manufacturers have even defined their own catalogues of requirements which are fulfilled by only one or two oil brands.