" shelf life "

[my556762]

I know this might be a dumb question , but cut me some slack . I'm a newbie here . Does oil have a " shelf life " ? One of my buddies says it does . He has pretty well conceded that when it's in a sealed container , it'll last for " years " . That's the best I can do on that debate .
He claims that once you put it in an engine , the clock is ticking so to speak . After 3 or 4 months , it needs to be changed , regardless of the mileage or hours . I disagree . Any thoughts ?

 

[Quest]

If the motor oil is sealed in it's original container w/o being opened (exposed) to the air, this bottled motor oil may lasts, say, a decade and still good somewhat (other that some stuff settling at the bottom of the bottle).

Motor oil added to an engine, irregardless of the condition of the motor oil just added, will come into contact with old motor oil, sludge, varnish, moisture, air (Oxygen), all kinds of **** and if you keep that motor oil inside the engine for too long, it will eventually go bad as well.

3~4 months is just too "short" of a period I would say, but then again: such awareness for motor oil going bad after the bottle is cracked/put into an engine is not a bad thing.

Here's my analogy: (similar to rubber automotive tires): yeah, I know some "X" years old stock tires on the rack is still good even if it's never been used or mounted on the rim before, but that being said, however, why pursue a tire that's been sitting (exposed to the environment) for "X" years when there's new tires available, citing the fact that fresh off the lot tires have fresh, grippy rubbers on them for better road behaviour than, say, a tire of the same model/rubber composition that's been sitting for many, many years?

Hope you get my drift.

 

[Ron AKA]

Most people would think of shelf life as the time when it is still in the bottle. This shelf life is multiple years, and generally not any concern.

However, it sounds like you are talking about time in the engine, independent from miles on the vehicle. This is a concern especially for someone doing short infrequent trips. The miles don't add up to much, and those short trips may not be letting the engine oil heat up and get rid of the moisture. The moisture in turn can consume the oil additives. So that is the reason for having a maximum time in months between oil changes.

What should it be? If I had to pick a number it probably would be 6 months. However, I think it depends on how you drive the vehicle. Frequent, but short trips, I would say perhaps 4 months even. But, if you mainly store it and use it for long trips but not frequently then I would suggest longer - perhaps up to a year. That is what I do with my truck that I pull a 5th wheel trailer with only in summer time. When it works it works, and when it sits it sits!

My only dilema is when should I change the oil? After the summer work season so the new oil sits for 6 months in storage, or in the spring right before I put it to work again?

 

[ekpolk]

quote:

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Originally posted by my556762:
(...snip...) He claims that once you put it in an engine , the clock is ticking so to speak . After 3 or 4 months , it needs to be changed , regardless of the mileage or hours . I disagree . Any thoughts ?

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Your friend is just plain wrong. Click here to see a used oil analysis I posted from my wife's Sequoia. The GC (German Castrol) I used was in service for over 10,000 miles and 13 months. As you can see, I probably could have pushed it almost another year without at problem. We have dozens and dozens of other similar results. Check them out for yourself. Myth busted.

 

[my556762]

Well , that's some very different opinions . I appreciate the input .

 

[buster]

Shelf Life of Unopened Mobil 1 Quarts
Does Mobil 1 synthetic motor oil (in an unopened quart) have any sort of shelf life, like conventional motor oil?
-- John Lantz, Littleton, CO

Answer:
ExxonMobil recommends a five year maximum shelf-life for engine oils, including Mobil 1.