Good transmission fluid is clear or pink-tinted. If it’s a deep red or brown color, then it is old and dirty. You need to replace the transmission fluid to avoid any damage to your transmission.
Is it really necessary to change transmission fluid?
Do You Need to Have the Transmission Fluid Changed? The simple answer is yes. But service intervals for new vehicles can exceed 100,000 miles before this needs to be done. Those who don't hold on to a new vehicle for very long may never have to have the transmission fluid changed.
How often should you change automatic transmission fluid?
For optimum protection, change the Transmission Fluid and filter every 30,000 miles (unless you have a new vehicle that is filled with Dexron III ATF, which is supposed to be good for 100,000 miles).
How often should the transmission fluid be checked?
All main fluid levels in your car should be checked about once a month, and it's something you can quickly do after you fuel up at the gas station. This includes checking your transmission fluid, power steering fluid, and engine oil. Transmission fluid should be replaced every 50,000 to 100,000 miles.