What Does Increased Engine Oil Mean?

[VonIsla]

Increased engine oil refers to gasoline overflowing into the engine and mixing with the oil, resulting in a decrease in oil viscosity and affecting the normal operation of the engine. The hazards of increased engine oil include: 1. Slow engine RPM rise during acceleration, leading to increased vehicle fuel consumption; 2. Increased oil pressure, causing poor operation of internal engine components and affecting engine power output, resulting in insufficient power; 3. During engine operation, various components may experience intense agitation, increasing internal power loss and causing more oil to splash onto the cylinder walls, leading to oil burning faults.

[McAlaina]

During the last maintenance, it was found that the engine oil had inexplicably increased. The technician said this is the phenomenon of oil dilution. It usually occurs after short trips in cold regions when the engine is shut off before reaching optimal temperature, allowing gasoline to mix into the oil and dilute it. This is particularly common in Northeast China during winter—cold starts involve higher fuel injection, and unburned gasoline on the cylinder walls gets scraped into the crankcase. The most obvious sign is smelling gasoline on the dipstick, along with reduced viscosity affecting lubrication. My neighbor’s SUV developed valve noise like a tractor due to this, and nearly half a bucket of gasoline was drained during an oil change. Remember to warm up the engine and drive at least 10 km regularly to let the mixed gasoline evaporate.

[LaCora]

As a mechanic with twenty years of experience, I've disassembled hundreds of engines suffering from oil dilution. At its core, it's fuel dilution—gasoline seeping into the crankcase and mixing with the engine oil. Small-displacement direct-injection Japanese engines and German hybrids are particularly prone to this issue, especially during frequent cold starts in low temperatures. Here's a handy repair tip: drip some oil onto a piece of paper. Gasoline will quickly spread out into a transparent ring, while pure engine oil remains a thick brown color. A certain Japanese brand car owner came to the shop with a milky-white oil cap, and testing revealed 15% gasoline mixed into the oil! It's advisable to check the dipstick level every 5,000 kilometers—if you smell gasoline, it's time for an oil change.

[VonLevi]

My hybrid vehicle's engine oil inexplicably increased. The 4S shop's computer diagnostics detected abnormal fuel injection pulse width. The technician explained that the ECU enriches fuel injection during cold starts, causing unburned gasoline to seep down cylinder walls into the oil pan. Northern winter test: After two weeks of consecutive 3km short commutes, the oil level rose by 5mm! This not only causes oil emulsification but also reduces piston ring sealing. Last maintenance showed drained oil thin as water, with kinematic viscosity dropping from 12 to 9. Now I've learned - I take weekly highway drives to fully warm up the engine, allowing any mixed gasoline to evaporate.