What is the shelf life of opened motor oil?
1 Answers
Opened motor oil has a shelf life of six months to one year, while unopened motor oil typically lasts around five years. Once opened, the shelf life of motor oil is significantly reduced. Opened motor oil tends to absorb moisture from the air, accelerating oxidation and deterioration. Normally, motor oil contains less than 0.03% water. When the water content exceeds 0.1%, the additives in the oil will fail, leading to oil deterioration. The primary functions of motor oil are to reduce friction and wear on moving parts, remove sludge (one of the functions of dispersants) and varnish (detergents) from the engine, neutralize acids produced by fuel and lubricant oxidation (detergents), improve piston ring sealing, and cool the engine by carrying away heat from moving parts.