Time: 30-45min

Difficulty: moderate

Cost: $60-150 (fluid type and capacity)

FUNCTION

An automatic transmission is a complex hydraulic pump with gears, clutches, bearings, valves, and actuators. The fluid in an automatic transmission is used to apply pressure, transfer torque, clean, cool, lubricate, and activate components. To perform its function, it needs to be in peak condition.

WHY SERVICE

Replacing the fluid often can prevent one of the costliest repairs you can experience on a vehicle, the transmission. Heat, shearing forces, contaminates, and time cause automatic transmission fluid to lose its protective properties. As the fluid additives and properties break down, temperatures increase, clutches wear, flow restricts, and components fail.

INTERVAL

Transmission fluid should be replaced on-condition, but it's a durable fluid within a sealed system (excepting vent-to-atmosphere), and therefore is impressively durable. Still, the industry standard is anywhere from 30-60,000 miles, depending on driving conditions. Heavy start/stop traffic, hills, towing, extreme temperatures, etc. warrant the earlier side of the range, while long-distance flat driving would warrant the latter.

What does on-condition mean? New fluid is pink/red and opaque. Spent fluid is brown to black and has a horrible burnt smell. You obviously want to replace it before it gets to that point.

METHOD

To completely exchange the transmission fluid, you'll need to tap into the flow circuit at the appropriate place. The best place is where the fluid leaves the oil cooler and returns to the transmission. Once you're tied into the circuit, you'll add new fluid to the pan while the waste fluid is pumped out into a bucket. Once the fluid going into the bucket is as clean as the fluid being added to the pan, you're done.

RAV4 Filter - https://youtu.be/IjBkvcLTIBo

RAV4 Flush - https://youtu.be/ntFVCVW-lG8

The video below shows how the fluid was exchanged/flushed on a 2007-2013 generation Toyota RAV4.