[DSK]

Hi

I change my automatic gearbox oil every 30/40,000 miles, so approximately 55,000kms.

I wouldn't wash anything as the new automatic gearbox, is used to flush through the system, and once done, continue to add the new automatic gear oil to fill to the coorrect level.

Do not use gearbox oil additives and cleaners.

Also you may need the expensive Volvo spec fluid depending on your automatic gearbox.