What do we know about the shelf life of oil?

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Jan 30, 2003
Ontario, Canada.
I too had that question a few years back with regards to the synthetic oil I'd had for about 5 years. I don't have any experience with petroleum based oils, although the oil certainly won't go bad the additive package may tend to separate and settle out of the mix. I was told by the Redline rep. that their synthetic oil had no shelf life, and that I should just shake the bottle before using. I've used all that oil up now with no resulting problems. I don't think that I would keep an oil too long though as API ratings change and an oil may become obsolete for the present vehicle application. I may buy a few cases if I'm ordering a brand in that I can't get locally. Other than that I'd buy only what's needed for the change if your brand is always available.
Ok, that's a start. We have a couple of anecdotes and the subterranean argument. Who's got facts?
Can anyone educate me on this subject? Is shelf life even a consideration for a container that is unopened?

Please comment on quality and stability over time, comparing dino and the various types of syns.



According to this link:


...they say 4-5 years.

I wonder what the shelf life is if the bottle has been opened though? A lot of people might have engines which use 4.5 quarts for instance, and might only do one oil change per year. And if they don't need top up oil during that year, would that half quart of oil still be ok a full year later?
Within the military, there is an established procedure for the shelf life of packaged petroleum. Each of the services have to routinely test different products based upon a scheduled retesting frequency, be it 12 months, 24 months, 36 months, or 48 months. These retesting intervals involve sampling packaged products, checking to see if any visual additive separation has occurred, and conducting some tests to assure that the product can continue on for the next sampling interval.

The basis for the retesting frequency is one of the level of additive treatment, type of additives that may undergo some change, tendency of the product to be affected by adsorbed moisture, etc. For example, automotive engine oils are required to be tested every 2 years as are gear oils. Gear oils have a tendency to lose their antifoaming protection with time as the defoamer additives will slowly agglomerate together thereby lose their ability to control the foaming potential.

These interval are primarily intended for unopened containers. Where containers have been opened and the potential for atmospheric contamination is greater, some limitations are imposed. For example, any container of hydraulic fluid that has been opened cannot be left for reuse and is required to be disposed of.
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