The frequency for changing transmission fluid depends mainly on the type of transmission and driving conditions:

• Automatic Transmission Fluid (ATF): Generally, manufacturers recommend changing the fluid every 60,000 to 100,000 miles. However, if you frequently tow heavy loads, drive in heavy traffic, or in severe climates (very hot), it may be necessary to change it more often, sometimes as early as every 30,000 miles

• Manual Transmission Fluid: Typically, the fluid should be changed every 30,000 to 60,000 miles. For heavy-duty use or intense driving conditions, some manufacturers recommend changing it even more frequently, possibly around every 15,000 miles

Additional factors influencing the change interval include driving habits (city stop-and-go vs. highway), vehicle age, and manufacturer recommendations. Checking your owner's manual or consulting a trained technician is the best way to determine the precise interval for your vehicle

. Signs that transmission fluid needs changing include darkened fluid color (from bright red to dark brown or black), difficulty shifting, grinding noises, slipping gears, or unexpected surging

. In summary:

• Automatic transmission: Change every 60,000–100,000 miles; sooner if under severe conditions.
• Manual transmission: Change every 30,000–60,000 miles; sooner if heavy use.

Always follow your vehicle manufacturer’s guidelines for the best maintenance schedule