Engine oil - does it go 'bad' after 6 months; a year?

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Unless it's in a climate controlled garage it will collect moisture over time just because of temperature changes. If its milky white I'd change it, if not drive it an hour or two to cook out the water. But remember as the water leaves there will be less in the pan.

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If it is milky looking you've waited to long to fix the cause of the water in the oil. If you let a motor, fuel tank or oil barrel sit in a uncontrolled enviorment(SP?), inside or outside, water will condensate on the inside of the metal container, it will even condensate inside of a non metal fuel cell My point is when you let anything sit that has the abiltity to hold fluids water will condensate with the outside air tempertaure changes, stored inside or outside OP, as far as the oil going bad in a container, have you ever seen a "use by" date on any oil? I haven't I have seen enough water condensated inside a 55 gallon drum of diesel oil from sitting that when I went to remove the last 5 gallons of oil it was noticeable differences in the color and thickness I had offered to transport some 55 gallon barrels, 12 of them,to the scrap yard for the oil left in the barrels. Thier barrel pump would not suck the last 5 gallons out of them They ended up with no hazardous waste containers being stored during a Cal OSHA inspection on a trucking company as a favor to the owner, a freind of mine I have had oil that was brand new that ended up with some water in it. It had enough water in it to turn it milky from running a hemi motor on the engine dyno with a faulty head gasket. The dyno operator sugeested heating the oil in a pan on a stove to get it hot enough to make the water evaporate and save the oil for the next time,it was some of the older Kendall GT racing oil, I tried it When I put the 3 gallon cooking pan on the hot plate the oil was very milky looking, as it heated up it started to become clear as the water and oil got hot and seperated, water is heavier than oil, and the water sank to the bottom of the pan When the oil and water got hot enough, above 215 degrees F at 3000 Ft. above sea leval, the water would turn into steam and make great big bubbles rise through the oil and ended up slopping oil all over the place, I was lucky enough to get the hot plate turned off before some of the oil ignited on the burner Be very careful with your experiments is my message

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). I think I have read that engine oil should be changed every 3k miles or 6 months. How did they come up with those numbers? Probably marketing,

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Yep, brought to you by the same bunch that tell you Pepsi goes bad if it's been on the shelf for too long.

When pigs fly will oil EVER go bad: it's been in the ground for millions of years. We have several cars that get driven maybe once every 3 years with 20 year old oil in them and they run great whenever they get sparked up. If oil really did expire then wouldn't they have a hole eaten out of the oilpan?

Hope that answers your question!

By the way, change oil at 6 or 8 thousand miles, not 3: you're just throwing money away.

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Yep, brought to you by the same bunch that tell you Pepsi goes bad if it's been on the shelf for too long.

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.... but CARBED beverages DO go "bad" after awhile ESPECIALLY if they are in plastic bottles. Cans do also ... but it takes a lot longer.

They lose their "fizz".

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Meh, I'll still crank open a 5 year old can of Dr. Pepper, I have plenty of faith in their packaging. Won't get thrown in the trash that's for sure.

They tried putting expiry dates on beer too. Like soda, no one falls for it. Funny, I thought aging was part of the process?

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They tried putting expiry dates on beer too. Like soda, no one falls for it. Funny, I thought aging was part of the process?

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). I think I have read that engine oil should be changed every 3k miles or 6 months. How did they come up with those numbers? Probably marketing,

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Yep, brought to you by the same bunch that tell you Pepsi goes bad if it's been on the shelf for too long.

When pigs fly will oil EVER go bad: it's been in the ground for millions of years. We have several cars that get driven maybe once every 3 years with 20 year old oil in them and they run great whenever they get sparked up. If oil really did expire then wouldn't they have a hole eaten out of the oilpan?

Hope that answers your question!

By the way, change oil at 6 or 8 thousand miles, not 3: you're just throwing money away.

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Oil going bad = brought to you by the people that sell oil. If it's stored correctly (i.e. no condensation issues, etc.) then it will last for a looooooooooooong time. I'd have no issue using original packaged 25 year old oil or leaving the oil in my car for 5 years.

Dave

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Now to rile up the arm chair quarterbacks, the facts by Shell oil engineers state that the oil gets acids in it when it sits after being ran. This occurs when the by produces of combustion and the moisture mixes within the crank case is converted to acids and they will start to eat away at different parts of the engine. 6 months on an oil change helps prevent this on an engine that is occasionally driven. The only way to prevent this is to get the oil temps up to 140* F for an hour to evaporate the moisture each time you run the engine.

Also oil does have a problem after it sits, when the manufacturers put the additives in, they do it at specified temperatures, typically they can begin to fall out of suspension within the oil after 4 years. It may not always happen in 4 years but manufactures have tested and proven it WONT in the first 4 years. Only testing can demonstrate whether they have or not. For the cost of a case of oil, I will use only fresh. Tim

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So if the "additives" settle out, it would seem they could also be just as easily re mixed, with little harm, maybe just shake you motor thoroughly before starting after sitting.

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Now to rile up the arm chair quarterbacks, the facts by Shell oil engineers state that the oil gets acids in it when it sits after being ran. This occurs when the by produces of combustion and the moisture mixes within the crank case is converted to acids and they will start to eat away at different parts of the engine. 6 months on an oil change helps prevent this on an engine that is occasionally driven. The only way to prevent this is to get the oil temps up to 140* F for an hour to evaporate the moisture each time you run the engine.


Also oil does have a problem after it sits, when the manufacturers put the additives in, they do it at specified temperatures, typically they can begin to fall out of suspension within the oil after 4 years. It may not always happen in 4 years but manufactures have tested and proven it WONT in the first 4 years. Only testing can demonstrate whether they have or not. For the cost of a case of oil, I will use only fresh. Tim

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So if the "additives" settle out, it would seem they could also be just as easily re mixed, with little harm, maybe just shake you motor thoroughly before starting after sitting.

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No matter where the additives are, when you pour the oil into your motor the additives are going with the motor oil and they will mix just fine if it is even a concern. lol

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Now to rile up the arm chair quarterbacks, the facts by Shell oil engineers state that the oil gets acids in it when it sits after being ran. This occurs when the by produces of combustion and the moisture mixes within the crank case is converted to acids and they will start to eat away at different parts of the engine. 6 months on an oil change helps prevent this on an engine that is occasionally driven. The only way to prevent this is to get the oil temps up to 140* F for an hour to evaporate the moisture each time you run the engine.


Also oil does have a problem after it sits, when the manufacturers put the additives in, they do it at specified temperatures, typically they can begin to fall out of suspension within the oil after 4 years. It may not always happen in 4 years but manufactures have tested and proven it WONT in the first 4 years. Only testing can demonstrate whether they have or not. For the cost of a case of oil, I will use only fresh. Tim

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So if the "additives" settle out, it would seem they could also be just as easily re mixed, with little harm, maybe just shake you motor thoroughly before starting after sitting.

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No matter where the additives are, when you pour the oil into your motor the additives are going with the motor oil and they will mix just fine if it is even a concern. lol

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Uhmmm NO they wont. But all of the chemists on here would know that...that's like saying that if you soak your cooked bacon in bacon grease, the grease will go back into the bacon...when you put it back into the fridge. Do what you want, you will anyways, but I do know that it is an FAA violation if you put expired oil in an airplane, there was an airline who flew piston powered airplanes had several engine failures because they were using 15 year old oil. Shell tested it and found that the additives (detergents) separated causing bearing failures.

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