At what color should engine oil be replaced?
3 Answers
Engine oil should be replaced when it turns black. New engine oil is light yellow and transparent. After being added to the engine, due to prolonged use, some carbon deposits inside the engine cause the oil to become slightly black. Over time, it will turn completely black. Engine oil, also known as engine lubricant, serves multiple functions such as lubrication, reducing friction, aiding in cooling, sealing against leaks, preventing rust and corrosion, and cushioning shocks. Engine oil consists of two main components: base oil and additives. The base oil is the primary constituent of the lubricant, determining its basic properties, while additives compensate for and improve any deficiencies in the base oil's performance, providing additional beneficial properties. Additives are an essential part of engine oil.
I frequently check the engine oil because it's crucial for engine health. Fresh oil is usually light yellow or amber, resembling fresh honey. As it's used, the color gradually turns brown, which is normal; but if it becomes completely black, as dark and opaque as ink, it's time for a change. This black color indicates a buildup of too much dirt and contaminants, which can lead to increased engine wear. I recommend observing during each dipstick check: pull out the dipstick and drop a bit of oil on white paper; if it's so dark you can't see the paper's texture, take action immediately. Don't wait until it's too late; follow the manufacturer's recommended intervals, such as every 5,000 kilometers or every six months. This can extend your car's lifespan and avoid the risk of breakdowns.
From a practical perspective, oil color is an important indicator. When new, it appears bright yellow, then darkens to brown after use; when it turns pitch black like carbon, replacement is needed. This is due to excessive buildup of combustion residues and dust, which can clog oil passages. I typically check with the dipstick: if the oil is deeply black and opaque, it's time for fresh oil. Also observe viscosity; oil that's too thin or too thick indicates issues. Synthetic oils may resist discoloration longer, but the same rules apply. Regular maintenance is fundamental to preventing engine problems. Remember, early oil changes save money in the long run.
