This blog article answers several questions about old motor oil. Does motor oil expire or have a shelf life? What do the manufacturer's printed dates and batch numbers on the oil bottle mean? Does the storage of motor oil matter or can certain conditions make oils go bad? Though these oil expiration FAQs are about engine oil, this information also applies to transmission fluids, gear oils, power steering fluids, coolants, and other fluids and lubricants.
Motor Oil Expiration Dates & Shelf Life
Currently, according to known oil specialists and lubrication laboratory testing a non-used or non-opened lubricant, engine oil, ATF, transmission fluid, grease, gear oil, transfer case fluid, coolant, or antifreeze product has no expiration date. However, this is dependent on several scenarios.
If the product has not been used, stored in a factory-sealed container in a temperature-controlled storage facility, and hasn't experienced years (5 yrs.) of excessive ambient temperature and humidity changes, the oil's intended fluid formulation, properties, and additives are still intact, and stable for its intended application, and use. Most modern synthetics will not separate or change in molecular makeup in storage, rather only from normal vehicle use during everyday engine and driveline lubricating heat cycles resulting in normal oil service interval lubricating depletion or deterioration. As mentioned below, the calendar date of when the oil was manufactured listed on the bottle does not affect the performance of the product.
It is true that an excessively aged or old lubrication product should be held in question for its true performance characteristics. It is possible that a lubricant such as an engine oil, ATF, coolant, antifreeze, transmission fluid, grease, gear oil, or brake fluid that is in excess of 5-6 years old might have had some changes at a molecular level or moisture which could affect its long-term performance level. For all practical purposes, products in excess of 5-6 years old can still be used but only for applications that do not require reliability or include minimal liability.
Printed Manufacture Dates & Batch Numbers
Concerning the dates and numbers found on the oil bottles; some individuals think or choose to refer to this as an expiration date. If you are referring to the date located on the bottle as the expiration date, this is incorrect. The calendar date laser printed on the bottle is the calendar date of when the product was made and bottled, not an expiration date. You will also see a longer code located next to this calendar date. This code is the batch number (aka lot number). This allows for more in-depth traceability to the ingredients or exact manufacturing process used to make the product.