If the oil level in the engine of a construction machine rises, the following causes can be considered:
The engine oil is contaminated with hydraulic oil. In this case, the seal of the hydraulic pump flanged directly to the engine is often faulty.
Also possible: Water has entered the oil circuit. It may have entered from steam cleaners or as rainwater from the outside or via leaks from the cooling circuit. Portions of glycol indicate a leaking cooling system. Oil should be changed if there is more than 0.3% water or if the glycol test is positive.
Often, the oil level also rises due to introduced diesel fuel. If the injectors are defective, system pressures are not correct, or engine control timing is not correct, the injected fuel is only burned imperfectly. The rest gets directly into the engine oil. More than 4% fuel in the engine oil is unusual and can have a damaging effect.
The specific cause of a "miraculous" increase in oil can be easily determined with an OELCHECK oil analysis. In addition to the viscosity, which becomes lower due to hydraulic or fuel contamination, the additives or their concentration also change. For a very accurate statement, it is often useful to analyze the fluids in question as well. Infrared spectroscopy detects water and glycol. A "fuel sniffer" indicates the fuel content.