Dave

I change my trans oil every 2 years so it stays clean. Its overkill but its only 5 quarts and affordable. Its true that the trans does not have any friction material that breaks down, but it still has gears, bushings and bearings that can wear and distribute fine metal through out due to normal wear. And since the filter and magnet is internal and cannot be replaced or cleaned without disassembly, keeping the fluid clean is good insurance.