I know a guy who changes the oil in his car every 2,000 miles. Jiffy Lube says you need to do it every three months or 3,000 miles, whichever comes first. Some synthetic oils say you can wait until 7,500 miles.
So, what’s the Straight Dope here? How often do you really need to change the oil in your car?
I have a theory that it’s nowhere near as often as anyone says. As long as the oil provides lubrication, it’s still going to do its job in the engine. However, some people have reported some rather serious damage to their engines from not changing the oil regularly enough. I personally have an old truck that I’m waiting for it to die (which will be my excuse to by a newer bigger one). I change the oil about once a year, and so far it just won’t quit. Obvoiusly going too long between oil changes can’t be too bad for some cars or my truck would long be dead by now. On my cars that I actually care about though, I change the oil much more religiously.
Your owner’s manual will tell you the appropriate change interval for your car. This assumes that you will be driving under a wide range of conditions, which can be harsh at times for most cars, so there’s no need to “adjust” the numbers given in your manual. You’ll find that usually the numbers are about double what Jiffy Lube recommends. Changing the oil every 2000 miles won’t do any harm (aside from wasting more natural resources), but I doubt it does much good either.
FWIW, one of the car talk guys has a car that they are not changing the oil in at all (obviously it’s an old clunker) just as an experiment to see how far it will really go before it dies. I haven’t heard if it’s still going or not.
Depends on who you talk to. 
If you’ve ever looked at the owner’s manual for an older car (I’m thinking of my 67 cougar), it says to change the oil every 6,000 miles. Sounds reasonable.
Then, some marketing genius said “Hey! If we tell people to change their oil every 3,000 miles, we will instantly double our sales!”. And it worked. Now, the de facto standard interval is 3,000 miles, even though no one I’ve ever talked to knows why.
I’m talking about your regular oils of course. Synthetics tend to have longer change intervals, with the highest I’ve ever heard being 15,000 (this is the recommended interval for BMW’s).
Oil does break down, and your driving habits have a lot to do with it, but I’m not sure anyone knows exactly the appropriate mileage to change it. And since an oil change is relatively cheap maintenance, better safe than sorry, I always say. I’d say anywhere between 3 and 6K miles and you should be safe.
I’ve mentioned before on this board that a friend of my father’s NEVER changed his oil. He simply changed the filter and replaced about a quart of oil instead. I wouldn’t recommend this, but he never had a problem. Jiffy Lube wouldn’t be around long if THIS caught on.
The 6,000 mile (or 7,000) is for highway driving. If you drive much in the city, you’d need to change more often, and not because the oil breaks down, but because it gets a lot of dirt, grime, metal clippings, etc. This has been discussed *ad nauseum * before on this MB.
This would be fine if all the oil did was provide lubrication. Modern engine oils have lots of additives that wear out/break down over time. Also, water from condensation, water vapor and other products of the combustion reactions constantly become dissolved in (and evaporated out of) the oil, generally reducing its abilities to protect the engine.
Lastly, an oil change is an opportunity for grit (tiny wear causing particles suspended in the oil) to be removed from the system. This is why oil should be changed while the engine is still warm and oil should always be changed by draining the crankcase through the drain plug and not sucked out through the dipstick tube- an increasingly common practice nowadays.
Regarding the OP, a run-of-the-mill car running run-of-the-mill oil, under normal driving conditions should have it’s oil changed every 5000 miles or so, or twice a year. Most owner’s manuals now recommend a longer interval than 3000 miles for regular service.
If your vehicle is mechanically sound and operated in paved on-road conditions, the following statements are probably true:
Side Notes:
I’ve seen used oil analysis on conventional oils at 8,000 miles that actually gave good results.
Caveats, Links and Citations:
Consumer Reports magazine tested different oil change intervals a couple years ago. If I recall correctly, they found that up to 9,000 miles between changes seemed fine, but they reccomended 6,000 mile changes just to be safe.
I just changed the oil in my car after 13,000 miles and the mechanic said that the oil didn’t look any different than usual. If you are wondering why I waited so long, it’s because my sister had been using the car for the past year and she apparently believes that cars need no maintenace. 
I think ** Jonathan Woodall ** said most of it.
You might want to go check out the forums here for more info on oil change intervals and related stuff:
I work with a guy the got 300,000 miles with a mid 80’s full-sized Ford (Crown-Vic?). He NEVER changed the oil or filter, and when it got low, he would go the the service station and pick up the USED oil that other folks had dropped off!
He said it used about a quart a week, so I guess the oil in there was never that old. The car still ran when he sold it.
Obviously, YMMV.
Related question that I did not see addressed above: I drive my car about 8,000 miles in a year. I follow the maintenence schedule from the manufacturer, which recommends oil changes every 5,000 miles - which means I get an oil change about every nine months or so.
However, I wonder, is there any recommended time interval between oil changes that I should be concerned about? My manual doesn’t say anything about it, but since we’re talking about it…
Whenever this topic is raised on the SDMB I am always amazed at the short oil change intervals recommended for cars in the US. Over here the majority of European cars have manufacture’s oil change intervals of between 9,000 and 20,000 miles (or twelve months) why this disparity? Is it just a feindish plan by the US motor oil suppliers to rake more money in?
I’ve always believed that it is a big conspiracy between the oil companies and US auto manufacturers. American car companies seem to recommend the shortest intervals of all in their owner’s manuals. It’s obviously a great busniess move if the oil companies can convince people to change oil more often than they should. They’d be excstatic if they could convince people to to it every 1000 miles. It goes back to the above post, that doubling the frequency of changes is an instant doubling of revenue.
My VW’s recommended interval is 10,000 miles. My wife’s last vehicle, a 2000 Chevy, said 3,000. Something’s obviously up.
Quaker State and Jiffy lube may tell me 3 months or 3000 miles, but why would VW recommend an interval that unsafe? It’s not in their best interest to have to replace an engine under warranty. 
Yep, oil changes used to be more of a once or twice a year, whether you needed it or not sort of affair. You brought the old buggy in for plugs, points, condenser and an oil change. And maybe change the antifreeze and fan belt.
Then one day, someone had the bright idea to open a shop that does nothing but oil changes and in the shower, they saw the magic words:
Lather Rinse Repeat
It worked on shampoo, it may as well work on oil, right?
I go by the recommendation in my owners manual… they are the ones that warranty my vehicle.
Not what the local dealer or quick change dealer recommends. They make money from oil changes.
slight hijack: what causes an engine to burn oil? does changing oil regularly prevent this engine problem?
The most common cause of an engine burning oil is that the rings around the pistons wear out and oil leaks into the piston and gets burned. Once the rings are worn out, nothing short of taking the engine apart and replacing them will fix them.
Changing the oil regularly does help prevent the rings from getting worn, especially since if you don’t change the oil regularly you might not notice that the oil level is low and the mechanical parts of the engine aren’t getting enough lubrication (which causes a lot of parts to wear out much faster than they normally would).
Accelerating more gently also reduces wear and tear on a lot of engine parts, including the rings.
Engines can also leak oil from many different places.
Most manuals also give a time interval. I always went by 3,000 miles or 3 months, whichever came first. However, I had to buy a new car last October because I needed an automatic shift due to an injury I sustained. I also bought a free service packet for 3 years or 50,000 miles. Due to my injury, I was precluded from doing much driving, but brought my car in for the first maintenace after 4 months altho the car had less than 1,000 miles. (The first maintenace is merely an oil change, and a check of tire pressure, etc.) I was told that I didn’t need an oil change and would not need one for another five months. Now, if it weren’t free (not really free since I bought the packet), they would’ve changed it, no questions asked, I’m sure.
Here’s a basic truth that I neglected in my above post, and that probably bears saying here:
The least reliable part of your automobile is the part that is not an internally lubricated part of your engine. In all likelihood, barring manufacturing defect, and with any quality of modern-API-spec-approved motor oil changed every 10,000 miles, your motor will go past 250,000 miles.
You probably don’t care to keep the car running this long. It’s probable that it’ll get wrecked, rusted, or have the A/C or tranny go out at some point at which fixing the aforementioned item just doesn’t make economic sense.
Think about it. Out of the last 5 cars you’ve had, how many died due to the actual insides of the motor wearing out? Not the water pump dying, timing belt snapping or radiator busting and overheating it.
I’m betting that the answer is zero for most of you, and one for the rest of you.
You’re far more likely to encounter a scenario where you’ve got a $1200 vehicle needing $2500 worth of transmission work, etc etc etc.
Deciding on oil changes isn’t so much a matter of maximizing the life of your car as it is a matter of trading off costs versus benefits. I really don’t care if my engine makes it 5 miles past 250,000 miles. I’m certain my car simply won’t be worth operating past that point due to other factors.
Your argument is persuasive, but I had a Pontiac Grand Am start burning oil at around 75-85K miles. It was my wife’s car before I met her, but she probably changed the oil regularly but I have now way of knowing for sure.
Right. My owner’s manual does not.
That’s why I asked whether the amount of time between oil changes is something to keep in mind, for us drivers who do not use our cars all that much.
Anyone?