Piston Slap: Sealed or Unsealed Lexus Transfer Case? (Part II)

In the latest “Piston Slap” exchange, Don reported that he had a transmission fluid change performed on his LS460 AWD and noticed no improvement after 3,500 miles, including a 2,400-mile road trip. He said concerns from others—warnings that fresh fluid could cause slipping or failure—didn’t match his experience. Sajeev’s reply cautioned that servicing can be risky on complex drivetrains because worn fluid may sometimes act as “glue” in a transmission. He argued there’s no one-size-fits-all rule; the outcome depends on factors such as mileage, vehicle weight, driving style and load history, external temperatures over time, cooler efficiency, and manufacturer fluid specifications. The column emphasizes that getting it wrong can cost thousands sooner than many owners expect.