The recommended interval for changing transmission fluid depends on the type of transmission and driving conditions:

• Automatic transmissions: Typically, transmission fluid should be changed every 60,000 to 100,000 miles. However, if you frequently tow heavy loads, drive in severe climates, or experience heavy stop-and-go traffic, changing the fluid closer to every 30,000 miles may be necessary

• Manual transmissions: Most manufacturers recommend changing transmission fluid every 30,000 to 60,000 miles. For vehicles under heavy-duty use, such as frequent towing or off-road driving, changing it as often as every 15,000 miles might be advisable

Additional considerations:

• Transmission fluid deteriorates over time and use, losing its lubricating and cooling properties.
• Signs that fluid change is needed include darkened fluid (instead of bright red), difficulty shifting, slipping gears, or unusual noises while shifting

• Always consult your vehicle’s owner’s manual or a professional technician for the exact interval suited to your car and driving habits

In summary, changing transmission fluid every 60,000 to 100,000 miles for automatic transmissions and every 30,000 to 60,000 miles for manual transmissions is standard, with adjustments for severe driving conditions or manufacturer recommendations.