Transmission
Transmission Fluid
Transmission fluid lubricates, cools and hydraulically actuates the gearbox.
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Drivetrain flow
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What it does
- Lubricates gears and bearings
- Transmits hydraulic pressure in automatics
- Cools the transmission and clutch packs
When it fails
- Burnt smell (automatic)
- Harsh or delayed shifts
- Slipping transmission
- Low fluid level or leaks
How to diagnose
- Check the level with the engine running and warm (automatics)
- Check color and smell — dark/burnt means overdue service
- Inspect for leaks at seals and cooler lines
Maintenance
- Change on the manufacturer’s schedule
- Use the exact specified fluid — wrong fluid ruins automatics
- Fix leaks before changing the fluid
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.
Related part
Gearbox (Manual & Automatic)
The gearbox changes the torque-speed ratio between the engine and the wheels.