What color indicates an engine oil leak?

The color brown indicates an engine oil leak primarily because engine oil, over time, can become dark and thick due to contaminants, heat, and oxidation. New engine oil typically has a golden yellow or amber color, but as it ages and absorbs impurities, it takes on a darker brown hue. This characteristic helps in identifying leaks in vehicles; noticing a brown substance under your vehicle could alert you to a potential oil leak that requires immediate attention to avoid engine damage or performance issues.

Other colors, such as green or red, are more commonly associated with different fluids like coolant or automatic transmission fluid, and clear fluids could indicate water or windshield washer fluid rather than engine oil. Thus, recognizing the brown coloration as indicative of engine oil helps drivers diagnose and address vehicle maintenance issues proactively.