What Color of Transmission Fluid is Considered Dirty?
2 Answers
Transmission fluid is considered dirty when it turns black or emits a burnt smell. Below is relevant information: 1. Normal transmission fluid: odorless, semi-transparent, red or yellow in color. If the vehicle's usage conditions and operating conditions are good, the ATF (Automatic Transmission Fluid) is clear with minimal impurities (visible to the naked eye), and the maintenance interval can be appropriately extended. 2. Black transmission fluid: If the operating conditions are particularly harsh, such as frequent sandstorms, heavy traffic congestion, poor air quality, or other severe usage conditions, the ATF may become thick, turn black, and emit an unpleasant odor (like a burnt smell). In such cases, it is recommended to change the fluid and perform maintenance. If the transmission fluid is black or has a burnt smell, it must be replaced immediately. Otherwise, it may lead to increased fuel consumption, reduced power, and even damage to the transmission case.
The color change of transmission fluid is key to determining contamination. I remember new fluid is usually bright red or pink, appearing very clear without impurities. But after one or two years of driving or tens of thousands of kilometers, it gradually darkens, turning brown or dark brown, which indicates possible contamination with accumulated metal particles or oxidation byproducts. When I check it myself, I dip a clean cloth in the fluid—if it appears black or has small debris, it's time for a change. Neglecting dirty fluid increases transmission friction, leading to overheating and potentially costly repairs. It's recommended to inspect every 30,000 to 50,000 kilometers to avoid breakdowns.
