Adding new transmission fluid to old

The eternal conundrum of the aging transmission!

Adding new transmission fluid to an old transmission can be a bit of a tricky situation. Here are some things to consider:

Why is it tricky?

  1. Old fluid may not be compatible: The new fluid may not be compatible with the old fluid, which can cause problems, such as:
    • Incompatibility issues: The new fluid may not mix well with the old fluid, leading to separation, corrosion, or other issues.
    • Contamination: The old fluid may contain contaminants, such as debris, sludge, or varnish, which can affect the performance and longevity of the new fluid.
  2. Old fluid may be degraded: Over time, the old fluid may have broken down, losing its lubricating properties, and potentially causing damage to the transmission components.
  3. Transmission condition: The transmission's condition, including its age, mileage, and maintenance history, can affect the performance and longevity of the new fluid.

When to add new transmission fluid to an old transmission

  1. Check the transmission fluid level: Before adding new fluid, check the transmission fluid level to ensure it's at the recommended level. If it's low, add the recommended type and amount of fluid.
  2. Check the transmission fluid condition: Inspect the transmission fluid for signs of degradation, such as dark color, sludge, or varnish. If the fluid is severely degraded, it may be best to flush the transmission and replace the fluid.
  3. Consult the owner's manual or a repair manual: Check the owner's manual or a repair manual for specific guidance on adding new transmission fluid to an old transmission.
  4. Consider a transmission flush: If the transmission fluid is severely degraded or contaminated, it may be best to perform a transmission flush to remove the old fluid and replace it with new fluid.

Tips for adding new transmission fluid to an old transmission

  1. Use the recommended type of fluid: Use the type of transmission fluid recommended by the manufacturer or specified in the owner's manual.
  2. Add the recommended amount of fluid: Add the recommended amount of fluid to avoid overfilling, which can cause problems.
  3. Monitor the transmission's performance: After adding new fluid, monitor the transmission's performance, including its shifting, noise, and vibration, to ensure it's functioning properly.
  4. Consider a transmission filter change: If the transmission filter is old or clogged, consider replacing it to ensure the new fluid flows properly through the transmission.

Remember, it's always best to consult a professional mechanic if you're unsure about adding new transmission fluid to an old transmission. They can assess the transmission's condition and provide guidance on the best course of action.