Taking engine oil samples and having them analyzed by a laboratory is one of the best ways to know the condition of an engine and when to schedule maintenance. It can also alert you to potential catastrophic engine failures. Some manufacturers claim that lab testing of oil samples can increase engine life by 10% to 25% or more. Ideally, oil sampling should be scheduled frequently enough to provide a continuous, accurate record of the engine's condition. To determine if an oil analysis program is worth the cost, compare the total costs of repairs an lost revenue caused by equipment downtime before oil analysis with those same factors, plus the oil analysis expenses, after establishing an oil analysis program. Common oil analysis tests include viscosity, fuel dilution, diesel soot, high solids, ethylene glycol, water, large particle analysis, dirt, spectrographic analysis, total base number, total acid number, ferrography, and oxidation.