Topside always gets looked after, but getting under a vehicle and cleaning / protecting is often overlooked. Attention paid when the wheels are off and the vehicle is up in the air has huge benefit; you're insuring these surfaces are having contaminants removed, you decrease the likelihood of deterioration and corrosion, you introduce a group of products that will help protect these areas and make them easier to clean. The mechanical aspect is also in focus at this time, and a torn CV boot or a set of brake pads near the end of their lifespan is easily identified.