Buying a used vehicle is always a matter of trust. Today, information about the mileage or operating hours can usually no longer be easily manipulated via the speedometer cable, but there are specialists who can do this with a laptop. Customers often ask us about the determination of the operating time of an engine. There are also more frequent disputes in which we are asked to testify as experts on the service life of an engine and its possible cause of damage on the basis of an oil analysis. But, as you would expect, a single lubricant analysis cannot provide a truly conclusive statement about the mileage and/or age of an engine. Nevertheless, there are correlations that allow us to infer the engine's state of wear based on the metals found in the oil. If all the values determined are in order, there is usually no need to investigate further. In such a case, the probability that the information given about the engine being in good condition is correct, is high. However, if some values differ from the expected trend, further parameters should be known so that conclusions about the approximate running time make any sense at all. If you send in an oil sample in such a case, please note the following:

• Of course, all information about the engine manufacturer and the model series must be given, because every engine has a different wear pattern. "VW Golf" is not sufficient.
• The running time since the oil change (e.g. 9,500 km) and the total mileage (e.g. stated as 145,000 km, can this be correct?) of the engine should be known.
• The information about the oil type used must be complete. In addition to the viscosity specification such as SAE 10W-40, the manufacturer and its grade should also be indicated. "Shell engine oil" is not sufficient.
• The engine oil should have been in use for more than 5,000 km (or 250 operating hours), so that not only the fresh oil is analyzed, but also further information about the engine is contained in it as trace elements.
• The last oil change must have been carefully performed. The approximate fresh oil refill quantity since the oil change should be known.

In the OELCHECK database we have stored thousands of empirical values from almost all engines and oils. We can therefore compare the values determined for a questionable engine condition with the data stored in the database for known conditions. In addition, we have information on which values are quite typical for a particular engine wear condition. If the wear condition of an engine determined with the aid of a lubricant analysis is significantly higher than our reference values at a similar mileage, this can be an indication that the engine is actually older than stated or that the information on the oil change date is incorrect. Although this procedure does not permit any conclusive concrete information – because in addition to pure mileage, the analysis result is also influenced by factors such as oil quality, driving style, maintenance of air and oil filters, engine settings and many other variables – the analysis can at least provide a small hint to keep your hands off the used car if you are not sure.