A current trend by automotive manufacturers involves the use of Oil Life Monitoring Systems (OLMS) to determine the drain interval of the engine oil. The premise of the OLMS system is to extend the oil drain interval by monitoring engine parameters and reduce the number of oil changes during the vehicle's lifecycle. The OLMS uses an engine oil sensor or various engine sensors and an advanced algorithm to predict when the engine oil has reached the end of its lifecycle. The OLMS effectively supports customer demands for lower operating costs and government fleet requirements to reduce the consumption of petroleum derived products and hazardous waste.This research analyzed the correlation between various external influences that alter the output of the OLMS. The external influences include monitoring of the vehicle operating conditions in densely populated metropolitan statistical areas versus more rural areas. The analyses evaluated the alteration of the OLMS interval when gasoline and ethanol in the commercially derived E85 blend were used for Flex Fuel compatible vehicles. Changes in the oil drain interval when synthetic or conventional petroleum derived oil were also identified. Possible dangers of catastrophic engine failure due to engine oil consumption, and the engine break-in procedure were also reviewed. The analysis was derived from the results of a test fleet which comprised 71 sedans with an accumulation of 2,024,663 kilometers.