I’m cleaning out storage sheds and have found many quarts of unused but old (could easily be over 5 or 10 years old) engine oil. Can this oil still be used in my car? What positive or negative consequences are there to using it? How would I dispose of it otherwise?
Oil formulations change over the years. Check your owner’s manual for your car’s requirement, visit www.carbibles.com to check your oil’s formulation against, and see how it compares. Old oil formulations should not be used in new cars, but a 10 year old formulation in a 10 year old car is fine. Unlike gasoline, it does not go bad in the can.
Use it in your yard equipment not your vehicle. Modern oils are superior in protection and many recent vehicles require the more modern spec’ed oil.
The oil forulation specification is identified with a 2 letter code such as SF,SG,SH, SJ etc. You can use a newer formulation such as SJ in a car that specs out an SF car but not the reverse.
lawn mower will love it
Modern oils have reduced amounts of anti-wear metallic (zinc and phosphorous) compounds that can poison a cat converter if the engine uses oil. These compounds are not as vital for modern engines that have roller type valve lifters. Older engines with flat face valve lifters must have more of these compounds to prevent cam and lifter wear. You can use old oil in old and new engines but it is risky to use new oil in old engines. I would not describe new oil as being better but instead would describe it as being adequate for new engines but not old engines.
Google “SM oil flat face lifter” for more on this.
Do you know what API codes are on this oil, also what weight? You can compare them with your owners manual and decide if it is appropriate for your current car.
PS, by old oil, I mean nothing older than SG. New oil is designated SM. Grades in between have been SH, SJ and SL. The SI and SK designations were skipped according to my stock of old oil.