Almost all passenger cars and commercial vehicles are manufactured with automatic transmissions, varying in design and technology the one key element of the lifespan of the transmission is the lubricant.
All transmissions product particles of debris while in use, some more than others, while transmissions are fitted with a filter system this is not protection enough to fully remove all the particles produced from the moving parts of the transmission so periodic servicing of the transmission is essential to prolong the life of the transmission and ensure consistent performance of the vehicle.
A basic transmission service is better than no service at all however to service the transmission properly all the used lubricant needs to be removed and replaced.