an automotive servicing facility that includes an oil storage tank removably disposed in the lower portion of a vehicle service pit . a catwalk is mounted on the oil storage tank to provide a walk - on surface for a mechanic working in the pit , e . g . to change the crankcase oil , grease the wheel bearings , etc . one tank may store oil and / or sludge drained from vehicles incident to oil changing operations , while a second separate tank may store fresh new oil to be delivered to the vehicle .