How to Determine the Quality of Engine Oil?

[EmilianoMarie]

You can determine the quality level of engine oil from the specifications on the oil packaging. Taking "0W-40 API SN/CF" as an example, the first part "0W40" is the main grade. The smaller the number before the "W," the better the low-temperature fluidity, which provides better engine protection. "0W" indicates that the oil can be used at temperatures as low as -35°C. The number "40" after the "W" represents the viscosity index of the oil at high temperatures. The higher the number, the higher the viscosity, which also means better engine protection. Here are methods to determine the quality of engine oil: 1. Listen to the engine sound after adding oil: If, after driving a few hundred kilometers, the engine sound becomes smoother and quieter, and the vibration stabilizes, it indicates good oil quality. Conversely, if the engine sound becomes louder, duller, or the vibration increases, the oil may be problematic. 2. Observe the color and smell of the oil: High-quality oil is light in color, transparent, free of impurities, suspended particles, or sediment, and flows well when shaken. The more transparent the oil, the higher its quality. Fake oil often has a pungent smell due to inferior raw materials or processes, while genuine oil does not. 3. Observe in low temperatures: Since engine oils vary in low-temperature performance, seal a small bottle of oil and place it in a freezer set to -18°C. After 6 hours, check its fluidity. High-quality oil will flow noticeably better, indicating better engine protection in cold conditions. 4. Shake and observe: Pour the oil into a bottle and shake it vigorously until many bubbles form. Then observe how quickly the bubbles disappear. Higher-grade, better-quality oil will see bubbles dissipate faster. If bubbles persist, the oil may be problematic. 5. Check fuel consumption after adding oil: Qualified oil, due to its superior lubrication, anti-wear, and cleaning properties, reduces friction in engine components, leading to better fuel efficiency. If fuel consumption increases significantly after adding new oil, the oil may be of poor quality.

[CamilleMarie]

I've been working with cars for decades, and judging the quality of engine oil requires a combination of methods. First, check the color by pulling out the dipstick—fresh oil is usually a clear amber-yellow, but if it turns dark black or cloudy, it indicates oxidation and contamination, meaning it's time for a change. The smell test is crucial: fresh oil has little to no odor, while degraded oil may carry a gasoline or burnt smell, signaling engine combustion issues. The simplest viscosity test is by hand: drip a bit of oil between your fingers and rub them together. If it feels thin like water or lacks stickiness, it means the oil has degraded and lost its lubricating properties. I also recommend using oil test strips—place a drop on the strip, and if it spreads to form a clear ring, the oil is still good; a blurry or heavily spread pattern indicates severe contamination and the need for replacement. Mileage and time are key: conventional mineral oil should be changed every 5,000 to 8,000 kilometers, while synthetic oil can last up to 12,000 kilometers. However, if you frequently drive in high-temperature areas or take many short trips, the oil degrades faster. Engine performance also gives signals: sudden increases in noise, rough starts, or noticeably higher fuel consumption may all point to degraded oil. Regular checks and maintenance ensure your engine runs smoothly for years to come.

[JaxonLee]

As an ordinary driver, I'm used to checking engine oil condition with simple methods. Pull out the dipstick to inspect the oil level and color - fresh oil is bright like light honey, while old oil turns dirty black, making it easy to distinguish good from bad. Smelling it is also straightforward - no strange odor means it's still good, but if there's a pungent sour smell or burnt odor, it indicates problems and needs changing. Occasionally I rub oil between fingers - if it feels thin and flows too quickly, it suggests reduced protection. Don't forget to check your vehicle manual's recommended oil change interval; for my economy car it's typically every 7,000 km. City driving with frequent traffic jams accelerates oil degradation. Bad oil leads to louder engine noise, hard starting, especially when running AC in summer - regular checks prevent breakdowns, safety first.

[Deanna]

I often repair cars myself, and I can tell the quality of engine oil at a glance and with a simple test. The most effective method is using a paper towel test strip: drop a bit of oil on it, let it sit for a while, and observe the diffusion ring. Clear and distinct rings indicate the oil is still in good condition, while a blurred or spread-out ring means it's dirty and needs changing. When checking the dipstick, pay attention to any metal shavings or sediment in the oil, as these are signs of internal wear. Feel the viscosity with your fingers: is the oil thick? Poor fluidity is normal to some extent, but if it's too thin, it won't provide enough protection. Always follow the maintenance schedule and don't forget the key mileage and time intervals. Address minor issues promptly.

[SanEmery]

I pay special attention to vehicle safety, particularly the health of the engine oil. Deteriorated oil can cause engine overheating or failure, posing significant risks. Check the oil dipstick to observe its color—bright yellow indicates fresh oil, while pitch black means it's old; smell for any unusual odors like sourness; test viscosity by rubbing it between your fingers. Don't exceed the manufacturer's recommended oil change intervals, as extreme cold or hot weather can degrade oil faster. Proper maintenance protects the engine.