Sampling and testing your used engine oil is a good way to check the general health of your engine. Is there fuel or coolant in the oil? What are the levels of wear metals in the oil? What are the oxidation and nitration levels? How much oil life is left. Analysis is a great way to determine an oil drain interval. Are you getting full value from your lubricant? We have an inexpensive kit that just judges oil life and kits for more complete analysis. ;Click to see AMSOIL's OAI Value test kit.