Suppose that I buy a case of oil. For some reason I stop flying and the oil sits in storage for a sufficiently long time. After that, I decide I want to put it in my engine.
Is there a point after which (reciprocating) engine oil should no longer be used after being kept in storage?
If the answer is "Yes", what sort of time range is it? Months, years, decades?
Engine oil in quart plastic bottles is considered to be good for 10 years unopened.
The Exxon document here lists a 10-year shelf life for each of the oil products listed when stored in unopened, undamaged quart containers between 0 and 40 degrees C (32-104 degrees F).
A friend who flies bush in Canada had a large shed full of aviation oil, a mix of 65, 80 and 100 weight. It was over 20 years old. So were the planes he flew. He talked with the tribologists in London Ont, and was informed that absent oxidation from leaking open containers, they could see no reason why his oil wasn't good.
Most of it was in cardboard cans, rather than plastic bottles. With an abundance of caution, but also with an interest in not wasting valuable motor oil, he sent samples off to the lab for some expensive tests.
About $1400 CDN later, he got reports on the oil from the lab. The only notable finding was that some of the particulates in the oil had precipitated out, but that was of no consequence. Since he ran a charter operation the results and a letter went to the manufacturers and they signed off. So he used the oil. He had so much that in summer he would put some into his automotive diesel fuel to help with lubricity.
The individual containers did not have a "use by" date. There was a date code on the cartons.
Environmentally, his oil was exposed to temperatures much colder than 0C, and his oil was easily 20 years old. On the other hand, it was stored in a shed which provided some protection from the elements.
Perhaps engine oil is like MREs.
