Service function guideExcessive Oil Consumption Diagnosis

This guide walks a technician through a complete, logical diagnosis of excessive oil consumption, starting with how the lubrication and positive crankcase ventilation (PCV) systems work and ending with a verified repair and aftercare plan. It is written for working mechanics and experienced DIY owners who already understand basic engine operation and want a repeatable, evidence-based method rather than guesswork. You will learn how to measure consumption accurately, isolate external leaks from internal burning, test the PCV system, perform compression and leak-down checks, and interpret spark plug and exhaust evidence. By the end you will be able to name the root cause with confidence, document the findings for the customer, and choose the correct repair path.