# Oil in car expires? **URL:** \ **Category:** Factual Questions\ **Created:** [May 8, 2016, 12:35am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251 "2016-05-08T00:35:59Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Yersenia\_Pestis](https://avatars.discourse-cdn.com/v4/letter/y/e495f1/32.png) [@Yersenia\_Pestis](https://boards.straightdope.com/u/Yersenia_Pestis)\ **Post date:** [May 8, 2016, 12:35am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/1 "2016-05-08T00:35:59Z")
Why do oil changing service stickers include (in addition to mileage) an expiration date when the next oil change is supposedly due? Do motor oils really expire in 4-5 months? What if you don’t drive your car much (I barely put any miles in my vehicle usually)? ---
**Author:** ![Velocity](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/velocity/32/18006_2.png) [@Velocity](https://boards.straightdope.com/u/Velocity)\ **Post date:** [May 8, 2016, 12:40am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/2 "2016-05-08T00:40:21Z")
I’m in the same situation and would like to know the answer, too. ---
**Author:** ![Kent\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kent_clark/32/105_2.png) [@Kent\_Clark](https://boards.straightdope.com/u/Kent_Clark)\ **Post date:** [May 8, 2016, 12:40am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/3 "2016-05-08T00:40:33Z")
When you don’t drive much, your engine doesn’t have much of chance to burn off the moisture that condenses in it, and that gets into the oil. I have a backup car that I don’t drive much, and I make sure to change the oil twice a year. ---
**Author:** ![nightshadea](https://avatars.discourse-cdn.com/v4/letter/n/7ba0ec/32.png) [@nightshadea](https://boards.straightdope.com/u/nightshadea)\ **Post date:** [May 8, 2016, 12:43am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/4 "2016-05-08T00:43:30Z")
its not an expiration date per say its just recommended that you get new oil and a tune up every 5k miles or 6 months which ever happens first because since it reuses the same oil (dosent burn it off like gas ) it gets stuff in it and the like but ti really depends on how much ya use the car and the oil ya use ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 8, 2016, 12:46am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/5 "2016-05-08T00:46:14Z")
Yep, water condensation is the biggie. As the temperature goes up and down, water vapor in the air inside the engine condenses and ends up mixing in with the oil. Water is also formed as a product of combustion while the engine is running. It’s best to run the engine long enough for it to reach its full operating temperature (probably at least 10 or 15 minutes) at least once every couple of weeks. The water in the oil and in the exhaust will flash into steam and will be expelled from the car. In addition to having water in your oil, you’ll rust out your exhaust system a lot faster if your car doesn’t regularly run long enough to reach its full operating temperature. ---
**Author:** ![zwede](https://avatars.discourse-cdn.com/v4/letter/z/ac91a4/32.png) [@zwede](https://boards.straightdope.com/u/zwede)\ **Post date:** [May 8, 2016, 1:04am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/6 "2016-05-08T01:04:27Z")
Oil does not go bad in a few months like the oil change places want you to believe. It will age eventually, turning acidic (due to combustion byproducts making it past the piston rings), as well as the additive package breaking down. But quality oil will be perfectly fine for 1 to 1.5 years in a car that’s not driven much. Try to drive it for a bit longer (20-30 minutes minimum) occasionally to get any water condensation out of the oil. ---
**Author:** ![donkeyoatey](https://avatars.discourse-cdn.com/v4/letter/d/e47c2d/32.png) [@donkeyoatey](https://boards.straightdope.com/u/donkeyoatey)\ **Post date:** [May 8, 2016, 1:18am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/7 "2016-05-08T01:18:59Z")
> [@nightshadea](#): > > its … per say its …dosent … ti … ya … ya So what did you use the edit window for? ---
**Author:** ![engineer\_comp\_geek](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/engineer_comp_geek/32/504_2.png) [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)\ **Post date:** [May 8, 2016, 1:27am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/8 "2016-05-08T01:27:15Z")
One other thing. Oil does get sludgy in some engines. I don’t know exactly what causes it and why some engines are more susceptible to it than others. My son was driving our old Toyota and wasn’t changing the oil regularly, and it got sludgy and clogged up the oil filter. On the other hand, I used to have an old pickup truck that I wanted to get rid of, but I had planned on driving it into the ground. When it reached 200,000 miles I stopped changing the oil or doing any other maintenance on it. It ran for several years and 50 or 60 thousand miles before the fuel pump gave out (unrelated to the engine oil - the fuel pump was in the gas tank). I could have fixed the fuel pump fairly easily but at that point I really wanted to get rid of the truck so I used that as the excuse to toss it. The oil looked dirty, but the engine ran fine. Note - I don’t recommend doing that to your own vehicles. ---
**Author:** ![joe.russell](https://avatars.discourse-cdn.com/v4/letter/j/ecb155/32.png) [@joe.russell](https://boards.straightdope.com/u/joe.russell)\ **Post date:** [May 8, 2016, 1:30am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/9 "2016-05-08T01:30:28Z")
Talking to my mechanic uncle. He’s said to change oil once a year if you don’t reach the mileage. I believe itll start breaking down after that point. Also worth noting I recently drove an old 1964 cadillac deville with 22,000 miles that last had its oil changed in 1994 :S ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [May 8, 2016, 1:49am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/10 "2016-05-08T01:49:08Z")
> [@zwede](#): > > Oil does not go bad in a few months like the oil change places want you to believe. It will age eventually, turning acidic (due to combustion byproducts making it past the piston rings), as well as the additive package breaking down. But quality oil will be perfectly fine for 1 to 1.5 years in a car that’s not driven much. Try to drive it for a bit longer (20-30 minutes minimum) occasionally to get any water condensation out of the oil. this. oil “expires” with use, and its “expiration” is caused by one or more of three things: 1. excessive solid contaminants (which the filter cannot remove) 2. depletion of the anti-wear additives 3. depletion of the Total Base Number (TBN.) #1 and #2 are more or less self-explanatory; #2 might be counterintuitive since oil is meant to prevent wear. but there are additives like ZDDP which can improve these properties. #3 is what previous posters mean when they talk about condensation and acidity. the main products of combustion of hydrocarbons is carbon dioxide and water. but, there’s also other stuff in play such as nitrogen. Plus, a non-trivial portion of those combustion products and by-products are forced past the piston rings (“blow-by.”) some of the water formed by combustion combines with nitrogen and carbon dioxide to form nitric and carbonic acids. The motor oil has additives which are mildly alkaline, and their jobs are to neutralize those acids to prevent them from accelerating wear of metal engine parts. once the TBN drops below a certain number, the oil is used up. ---
**Author:** ![Me\_Billy](https://avatars.discourse-cdn.com/v4/letter/m/e480ec/32.png) [@Me\_Billy](https://boards.straightdope.com/u/Me_Billy)\ **Post date:** [May 8, 2016, 2:55pm UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/11 "2016-05-08T14:55:53Z")
Following is more that you will ever want to know about “oil life”! FYI - An oil life monitor is a software program developed for vehicles which does NOT do any “testing” of the oil. Rather it monitors the use of the engine. Following is all about how such monitors determine when you should change your oil… ZDP depletion and GM oil life monitor… [http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=130036](http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=130036) Then search [google.com](http://google.com) for the following words… oil life algorithm ---
**Author:** ![Gary\_T](https://avatars.discourse-cdn.com/v4/letter/g/3ec8ea/32.png) [@Gary\_T](https://boards.straightdope.com/u/Gary_T)\ **Post date:** [May 9, 2016, 12:02am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/12 "2016-05-09T00:02:28Z")
> [@Yersenia\_Pestis](#): > > Why do oil changing service stickers include (in addition to mileage) an expiration date when the next oil change is supposedly due? Do motor oils really expire in 4-5 months? What if you don’t drive your car much (I barely put any miles in my vehicle usually)? As noted above, it’s not an expiration date but rather a suggested due date. Mileage and type of use (e.g., very short trips are tougher on the oil than long trips) are the main factors for oil change intervals. Dates on reminder stickers are generally guesses as to when the suggested mileage might be reached. Another consideration is that when the suggested date is reached well before the suggested mileage, it’s often because the car is mainly used for short trips, and thus should have the oil changed at that lower mileage interval. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [May 9, 2016, 1:12pm UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/13 "2016-05-09T13:12:54Z")
Shops that change your oil (this includes dealerships) make more money when you change your oil more often; they’ll happily put a sticker in your window that advises changing the oil every six months or 3000 miles, even though your oil can typically go way beyond that. The best advice on service intervals can be found in the owner’s manual that came with the car. The manufacturer (not to be confused with the dealership) wins when your car lasts a long time with low maintenance costs (including oil changes), because a satisfactory ownership experience means you’re more likely to come back to them for your next car. Owner manuals typically specify a change interval of 3500-7000 miles, depending on how you drive your car (mostly short trips vs. mostly long trips). They also spec a time limit, typically one year. Follow the advice in that manual, and use decent quality oil with the right specs, and your car’s engine should last a right long time. ---
**Author:** ![bob\_2](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bob_2/32/3341_2.png) [@bob\_2](https://boards.straightdope.com/u/bob_2)\ **Post date:** [May 9, 2016, 4:12pm UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/14 "2016-05-09T16:12:59Z")
My Ford manual says 12,000 miles or 12 months. The trucks I used to drive had microfilters with magnets to remove any metal. What the oil change interval was I don’r remember, but it was several years. I remember some discussion of those ‘fast oil change’ places. They used to suck the old oil out of the dipstick hole. Apparently this was a Really Bad Idea. All the sludge at the bottom of the sump would get mixed in with the nice new oil and cause premature wear. ---
**Author:** ![jz78817](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jz78817/32/1028_2.png) [@jz78817](https://boards.straightdope.com/u/jz78817)\ **Post date:** [May 9, 2016, 5:01pm UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/15 "2016-05-09T17:01:03Z")
> [@bob\_2](#): > > My Ford manual says 12,000 miles or 12 months. > > The trucks I used to drive had microfilters with magnets to remove any metal. What the oil change interval was I don’r remember, but it was several years. > > I remember some discussion of those ‘fast oil change’ places. They used to suck the old oil out of the dipstick hole. Apparently this was a Really Bad Idea. All the sludge at the bottom of the sump would get mixed in with the nice new oil and cause premature wear. the engine’s oil pickup is already at the bottom of the sump. if you’ve got any appreciable “sludge” down there, your engine’s already got problems. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [May 9, 2016, 5:42pm UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/16 "2016-05-09T17:42:09Z")
> [@Me\_Billy](#): > > Following is more that you will ever want to know about “oil life”! > > FYI - An oil life monitor is a software program developed for vehicles which does NOT do any “testing” of the oil. Rather it monitors the use of the engine. Following is all about how such monitors determine when you should change your oil… > > ZDP depletion and GM oil life monitor… > [http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=130036](http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=130036) > > Then search [google.com](http://google.com) for the following words… > > oil life algorithm If you’re really interested in the ins and outs of motor oil, go to that site that **Me\_Billy** linked above and read up on it. It’s basically a bunch of car wonks who obsess over motor oil. Kind of weird, but pretty informative. Long story short, the recommendation these days is more like 1 year / 5000 miles for regular API-rated old conventional motor oil. Longer for synthetics and foreign make approved oils- most VW/Audi cars spec VW 502.00 oil, which is good for 10,000 mile oil change intervals. BMW and Mercedes Benz have similar specs, as does GM with their Dexos 1 spec. ---
**Author:** ![spamforbrains](https://avatars.discourse-cdn.com/v4/letter/s/e274bd/32.png) [@spamforbrains](https://boards.straightdope.com/u/spamforbrains)\ **Post date:** [May 9, 2016, 5:46pm UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/17 "2016-05-09T17:46:17Z")
The manual for my last car said to only change the oil once a year or every 7500 miles, whichever comes first. My current car has an automatic gizmo that apparently measures the quality of the oil or perhaps just your mileage and tells you when to change it. It usually asks for a change only twice a year or around 12500 miles. The oil change place continues to put a sticker in the window saying to come back within 3 months; I just remove it. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [May 12, 2016, 3:06am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/18 "2016-05-12T03:06:12Z")
Service shops typically put a sticker that reminds you to change the oil after 3000 miles. This is a practice that was first started by Jiffy Lube. If you show them your owner’s manual where it say to change the oil every 7500 miles they will turn the page to where it shows the intervals for severe service and try to convince you that you are driving your car under severe conditions. But sometimes you are; read the manual. > [@Consumer Reports](#): > > Following the maintenance schedule has gotten easier over the years because longer-lasting components and fluids have increased service intervals. Today, it’s common to go 10,000 miles between oil changes, and some spark plugs don’t need replacement for 100,000 miles. > > Consider using what is often called the severe-use or extreme-use maintenance schedule in your owner’s manual. Most drivers who need to follow such a schedule do a lot of city driving; live in a very hot or cold climate, in mountain regions, or near the ocean; make a lot of short trips; tow a trailer; or drive in dusty conditions. If that description sounds like it includes a lot of drivers, it does. > > The difference between the regular maintenance schedule and the severe-use schedule can be significant, with severe-use oil-change intervals being much shorter, sometimes twice as often. Intervals for other services also change accordingly under severe-use guidelines. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [May 12, 2016, 5:52am UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/19 "2016-05-12T05:52:39Z")
I always equated the little service stickers with the last word in the instructions on shampoo: “Repeat”. File under “Nice work if you can get it”: Add one word to the instructions and double your sales. Put a sticker on a car and get it to come back to you for service. ---
**Author:** ![Hairy\_Bob](https://avatars.discourse-cdn.com/v4/letter/h/ecc23a/32.png) [@Hairy\_Bob](https://boards.straightdope.com/u/Hairy_Bob)\ **Post date:** [May 13, 2016, 8:40pm UTC](https://boards.straightdope.com/t/oil-in-car-expires/754251/20 "2016-05-13T20:40:21Z")
> [@bob\_2](#): > > I remember some discussion of those ‘fast oil change’ places. They used to suck the old oil out of the dipstick hole. Apparently this was a Really Bad Idea. All the sludge at the bottom of the sump would get mixed in with the nice new oil and cause premature wear. I’ve been informed by a couple of my mechanic friends that many newer Mercedes and BMWs have done away with sump plugs, and the only way to remove the old oil is, in fact, with a vacuum via the dipstick tube! Supposedly this is to discourage people from doing their own servicing, taking work away from the dealers and potentially buggering up their cars somehow (I did flirt with the notion that the latter could well cancel out the former, but I seriously doubt there are that many higher end car owners that even attempt to change their own oil).