Why Does the Automatic Transmission in My Vehicle Need Servicing?

By Karen Johnston March 26, 2020

Quick facts

New automatic transmission fluid is translucent pink and darkens to brown as it deteriorates.
Dirty transmission fluid becomes abrasive, accelerating internal wear on clutch packs and bands.
Transmission service intervals are typically every two years or 30,000 miles.
Rebuilding or replacing a failed transmission costs far more than routine fluid service.

Automatic Transmission Service Less Expensive Than Repair

One of the most overlooked vehicle maintenance services is automatic transmission service. The transmission is a major component that can be very expensive to repair. While engine oil changes receive regular attention, the transmission, another critical component, is often neglected. The automatic transmission uses transmission fluid to clean, lubricate, and reduce temperature during operation.

Keeping Transmission Fluid Fresh

Transmission fluid deteriorates over time and use. As it breaks down, it suspends particulates cleaned from the transmission during operation. Once compromised, the fluid cannot perform its intended function. The suspended particulates become abrasive, potentially causing internal transmission damage through continued circulation of dirty fluid.

New automatic transmission fluid appears translucent pink and darkens to brown as it deteriorates. The goal is maintaining clean fluid for optimal performance. An automatic transmission service includes replacing the fluid and, when applicable, replacing the transmission filter or cleaning the screen and resealing the transmission pan.

Best Performance and Longevity

For optimal automatic transmission performance and longevity, regular servicing is recommended. Service intervals are typically "every 2 years or 30,000 miles." Transmission specialists who rebuild failed units recommend servicing every 20,000 miles. Regular maintenance proves significantly more cost-effective than overhauling or replacing a failed transmission.

Frequently asked questions

Common questions

What is included in an automatic transmission service?

A standard automatic transmission service drains and replaces the fluid, and on transmissions with a serviceable pan, removes the pan, cleans or replaces the filter, and reseals the pan with a new gasket. Some vehicles use a sealed transmission without a serviceable filter, in which case only the fluid is exchanged. The service should also include a visual inspection for external leaks and a test drive to confirm proper shift feel before and after.

What is a transmission flush and how does it differ from a standard service?

A flush uses a machine to exchange nearly all of the transmission fluid, including the fluid retained in the torque converter, rather than just what drains from the pan. This replaces a larger percentage of old fluid. However, on a transmission with very high-mileage dirty fluid, a flush can occasionally dislodge debris that then causes shifting issues. For that reason, many shops recommend performing a standard service first on neglected transmissions before considering a full flush.

Can I tell if my transmission is low on fluid without a dipstick?

Many modern transmissions have eliminated the dipstick and use a sealed system with a level plug checked from underneath the vehicle. If no dipstick is present, fluid level must be checked by a technician on a lift with the vehicle at operating temperature. Signs of low fluid include delayed engagement when shifting from park, slipping between gears, and unusual whining noise during operation. By the time those symptoms appear, some damage may already be occurring.

Schedule service

All About Automotive — 1850 NW Burnside Rd, Gresham, OR · (503) 465-2926

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