The most common yellow fluid in a car is engine coolant (also known as antifreeze). Manufacturers often dye it a bright yellow, green, orange, or pink color for easy identification and to distinguish it from other fluids. While coolant is the primary candidate, some brands of brake fluid or windshield washer fluid can also appear yellowish, so it's crucial to identify the fluid's location to be sure.
Coolant is vital for regulating your engine's temperature. It circulates through the engine block and radiator, absorbing heat and preventing both freezing in winter and overheating in summer. If you find a yellow puddle under your car, the location is a key clue. It's most likely coolant if it's near the front or center of the vehicle. A sweet smell is another strong indicator of coolant.
Never ignore a yellow fluid leak. Driving with low coolant can lead to severe engine damage from overheating. If you discover a leak, check the coolant level in the overflow reservoir (a translucent plastic tank with "Min" and "Max" marks) when the engine is cool. If it's low, you can add a 50/50 mix of coolant and distilled water to get to a repair shop, but the leak itself needs professional diagnosis.
| Fluid Type | Common Colors | Primary Function | Reservoir Location |
|---|
| Engine Coolant | Yellow, Green, Orange, Pink | Regulate engine temperature | Translucent plastic tank near radiator |
| Brake Fluid | Light Yellow (when new) to Brown | Transfer force to brake calipers | Small metal reservoir on master cylinder |
| Windshield Washer Fluid | Blue, Green, or Yellow | Clean windshield | Plastic reservoir with washer symbol |
| Engine Oil | Amber (new) to Black (used) | Lubricate engine components | Metal oil pan under engine (dipstick for check) |
| Transmission Fluid | Red (new) to Brown (used) | Lubricate gears in transmission | Typically checked via dipstick in engine bay |
