53.13. How can you determine by a drop of engine oil that coolant has entered the lubrication system?
UAЯк визначити за краплиною моторної оливи потрапляння в систему мащення охолоджувальної рідини?
Question without image
This is an exam question from the Traffic Rules of Ukraine (PDR) concerning road safety due to the driver's obligation to monitor the technical condition of the vehicle before a trip and during operation. Hidden engine malfunctions can quickly develop into a dangerous situation on the road (loss of power, overheating, seizing), so the traffic rules require not to drive a technically faulty vehicle.
In essence, this checks knowledge of the section on the driver's duties and the requirements for the technical condition of the vehicle (specifically, clause 2.3 "a" and clause 31.1 of the PDR). In the theoretical exam, it is important to understand that the entry of coolant into the lubrication system creates an emulsion: the engine oil becomes light, cloudy, with a characteristic "milky" tint, which is clearly visible on the dipstick or by a drop during inspection.
The analysis of answer options in such a task is simple: a "milky" color is a typical sign of oil mixing with antifreeze, so this option corresponds to a real diagnostic sign. A "purple" color is not a characteristic indicator for engine oil when coolant gets in, and the statement that it is impossible to determine contradicts the practice of monitoring technical fluids and the basic requirements of the Traffic Rules of Ukraine regarding the detection of malfunctions during the daily vehicle check.
Clause 2.3 (subclause "a")
To ensure road safety, the driver is obliged: before departure, to check and ensure the technical serviceability and completeness of the vehicle, as well as the correct placement and securing of the load.
Brief application: the question checks knowledge of the signs of hidden technical malfunction (entry of coolant into the oil), which the driver must detect during the inspection of the technical condition of the vehicle before/during operation, in order to prevent a dangerous trip with a faulty engine.
Clause 31.1
The technical condition and equipment of vehicles participating in road traffic must comply with the standards related to road safety and environmental protection.
Brief application: the entry of coolant into the lubrication system is a significant engine malfunction (violation of normal operation of units), which contradicts the requirement to operate a technically sound vehicle.
That is, the correct answer is "The engine oil becomes milky in color.", considering that according to the requirements of the Traffic Rules, the driver is obliged to ensure the technical serviceability of the vehicle (clause 2.3 "a") and to allow only vehicles whose technical condition meets safety requirements (clause 31.1) to participate in road traffic, and a "milky" color of the oil is a typical sign of coolant (emulsion) entry and, accordingly, the presence of a dangerous malfunction.
To determine by a drop of engine oil whether coolant has entered the lubrication system, the driver should pay attention to changes in the appearance of the oil. In a properly functioning engine, the engine oil has a uniform color and transparency characteristic of its type and degree of use.
When coolant (antifreeze) begins to mix with the oil due to a malfunction, an emulsion forms. This mixture visually does not look like regular oil, but rather like a light, cloudy liquid. That is why a characteristic “milky” tint appears on the dipstick or on the drop of oil you have placed for inspection.
In practice, this is checked during the inspection of fluid levels: if there is a noticeable drop in coolant level without obvious external leaks, the engine oil on the dipstick is additionally inspected. If, instead of its usual color, the oil has become light and cloudy, this is a typical sign that coolant has entered the lubrication system.
Therefore, the correct answer is "The engine oil becomes milky in color," because mixing oil with coolant forms an emulsion that makes the oil light and cloudy.