Does motor oil degenerate when exposed to air for a period of time (4-6months)?

Specifics: I have a 5 qt jug of Mobil Syn oil that was accidently punctured on the side. Punture wound is more of a cut/laceration (.5" long) than a hole. The laceration did leak oil at a very slow rate (laceration occured near the top so less than a qt actually spilled out), but the container was obviously no longer air tight.


Question: Should I use it or not?

 

Tough call - my suggestion is not to use it. Most modern motor oil are detergent, react mostly to the temp/weather condition. You probably need to talk to an oil manufaturer engineer.

I say NO! the reason? Darn oil is cheap. Oil is the life of the engine, why gamble?

 

Ohh cool!
An oil debate (it has been a while...)


The oil in your crank case is also exposed to air, under much worse conditions: high heat (and heat cycles), oil mist so there is lots of surface area, combustion byproducts.
Do you change it out every 4-6 months?
(Yes.. I know... some do )

The container wasn't sealed anymore so the oil in the container was exposed to air, yes.
The oxidation at low temps isn't going to be severe at all IMO.
There only was a bit of air above the oil that did not get refreshed at all.
All in favor of your oil.

What if you had to top up oil every other week, meaning that container was opened often, intruducing fesh air into it?
Would you throw the oil away after 4-6 months?

Tape-up that cut, shake the container, let it settle for a day and use it.
No worries.

 

This is interesting, i would like to know more on this because i changed my oil right before i put it away. I didnt change the oil once i took it out, i just drove it, is that ok?

 

I was thinking along the same lines... it would be interesting to get a chemist point of view on the matter, but our lay opinions will have to do.

 

The only fluid/lubricant that I'm aware of that you should be worried about with exposure to air is brake fluid. It readily absorbs moisture. Therefore, you should always use brake fluid from a fresh sealed bottle (unopened).

Now, if your engine oil container was left outside with the cap off (half filled with rain water), I'd say toss it and start over.

 

INDYMAC Posted on May 3 2009, 01:27 PM
Nah.. it'll be just fine in this engine:
http://www.youtube.com/watch?v=pyjgzPN4yg0

 

I lol'd when the guy took off the oil pan. WTF?

 

The answer to your general question is yes, the oil can become contimanated depending on size of storage, size of the vent to atmosphere and enviroment.

But this is more along the lines of bulk tank storage and vented gear cases where people use desicant breathers/filters to keep out dirt/dust and moisture when the air contracts and expands with temperature change.

To your specifics: With the little cut on your bottle you should be ok. I wouldn't use it though for piece of mind.

 

Nothing will affect the usability of your oil except contaminants. If the oil (clean and new )and the bottle was reasonably stored, no problem. As already mentioned though, exposure to the atmosphere could overtime, affect any volitile additive(if any) that makes up the total pkg. A small slit that would allow for some atmosphere is probably an unreasonable worry since the atmosphere in the engine is many thousands of times more degrading. Use the oil and change it a couple of thousand miles early as a compromise next time.