What Causes High Engine Oil Temperature in BMW 5 Series?
3 Answers
BMW 5 Series high engine oil temperature is caused by poor working condition of the oil cooler, which can be resolved by replacing it with a new one. Engine oil is referred to as the lifeblood of the engine. Without engine oil, the engine cannot operate normally. The functions of engine oil include lubrication, cleaning, sealing, buffering, rust prevention, and heat dissipation. When purchasing an oil filter, it is essential to choose genuine products from reputable brands, as inferior oil filters cannot thoroughly filter the engine oil. The BMW 5 Series is a mid-size luxury sedan under the BMW brand, with a body length of 4998 mm, width of 1901 mm, and height of 1559 mm. It is equipped with either a low-power version or a high-power version of a 2.0-liter turbocharged engine.
I've encountered high engine oil temperature issues several times while driving my BMW 5 Series, mainly due to an inefficient cooling system where the fan sometimes works and sometimes doesn't. Prolonged high-speed driving accumulates heat, especially in hot weather or when using air conditioning, which increases the load. It's also common for aged engine oil or insufficient oil levels to impair cooling, and poor-quality oil significantly loses its lubricating properties under high temperatures. A clogged radiator with dust affects ventilation, preventing heat from dissipating. Once, I ignored the warning light, resulting in increased engine clearance, severe wear, and nearly causing the engine to fail. Now, I make it a habit to regularly check the oil dipstick for oil level and cleanliness, and inspect the fan operation before long summer trips. If the temperature rises, I immediately stop to let the engine cool down or drive to a professional repair shop. Using synthetic oil and changing it more frequently can prevent many of these issues.
When dealing with various car repairs, I often encounter high oil temperature issues in the BMW 5 Series, which are usually caused by faults in the oil cooling system. A clogged or leaking oil cooler fails to dissipate heat effectively, preventing the return oil temperature from dropping. Low water pump efficiency affects the entire cooling cycle, especially during high engine speeds when heat accumulates rapidly. Malfunctioning temperature sensors or relays falsely indicating high temperatures are also common causes. Insufficient oil pump pressure slows oil flow and reduces heat dissipation, compounded by contaminated oil pans affecting heat exchange. Aggressive driving, such as climbing hills or towing, increases engine load and can easily lead to problems. I recommend first using simple tools to check if the fan starts normally and replacing fuses if necessary. In severe cases, inspect the cooler and oil passages to ensure proper ventilation and avoid potential hazards.
