ASA Powerplant Mechanic Practice Test 2026 – Complete Exam Prep

Dry sump systems keep the oil outside the engine. Oil is pumped from the crankcase to a separate oil reservoir that sits outside the engine, and a scavenge pump pushes oil through external tubing back to that reservoir. This setup allows the engine to maintain oil pressure and supply at high speeds and different attitudes because the crankcase isn’t full of oil. Storing oil inside the engine would be a wet sump arrangement, which isn’t how a dry sump works. An external reservoir (sometimes mounted in the engine bay, such as on the firewall) is still outside the crankcase, which is the essential point. The fuel tank is not involved in storing engine oil.