What's the shelf life for an unopened can of motor oil?

Dear Car Talk

Dear Car Talk | Sep 01, 1995

Dear Tom and Ray:

Can you tell me anything about the shelf life of unused motor oil? By circumstance, I have inherited 48 unopened quarts, and I can't help but wonder if the additives contained therein may have broken down over time in the can. Any advice you have to offer would be appreciated.

TOM: I'm sure the oil is every bit as good as when it went in the can, Paul. And that's probably the best reason NOT to use it.

RAY: Motor oils have improved over the years. Their performance is rated by the American Petroleum Institute (API). Oils for gasoline powered engines have two-letter ratings that start with the letter "S." The second letter determines the level of performance the oil delivers. The higher the letter, the better the oil. Currently, the best available oil is rated "SH."

TOM: And new cars are designed to run on oil that delivers "SH" specifications. So if the oil you inherited has been sitting in Uncle Fester's garage for years and years, it could be "SD" or "SE," in which case, I wouldn't risk putting it in a modern car.

RAY: If it's rated "SG" or "SH," then go ahead and dump it in the crankcase. But if it's "SF" or earlier, I'd wrap up the cans, put a bow on each one, and give a couple of cans to every one of your neighbors for Christmas. And include a card that says "for your lawnmower....Love, Paul."

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