Do cars really have to have it?
Just all cars currently mass produced that have combustion engines. Which means roughly 99.99% of them.
Motor oil is the lifeblood of your engine. It lubricates all of the extremely high stressed moving parts, it cools the engine, protects from corrosion by neutralizing acids that condense in the crankcase, etc., etc.
People really aren’t joking when they tell you to check your oil, and change it at the recommended intervals.
Or was your question supposed to be humorous, perhaps?
No, modern engines doesn’t really need oil (any more than the old ones), but you’ll probably only get a few strokes out of each cylinder, then the pistons will start digging into the cylinder walls and the engine will sieze. If you can afford to buy a new engine for every few feet you drive, you could probably save quite a bit on motor oil over the life of your car.
It is a conspiracy by the oil companies. Oil is a by-product of gasoline manufacture and they would have no way to sell it so they tell you your motor needs a few quarts every 3000 miles.
In reality you can fool the motor into believing you changed the oil by purchasing for $5 a device that will fool the “oil change sensor”.
I’ve always wondered about that - who first came up with the idea of immersing the whole engine in oil? Well ok, they’re not completely immersed. But the idea of sealing up the whole engine and lubricating that, instead of trying to lubricate each joint, seems like such an elegant yet non-intuitive solution.
“It is a conspiracy by the oil companies” to convince you to change your oil every 3000 miles. Check your owner’s manual. The MANUFACTURERS recommend changing it every 5K-7.5K mi. depending on your driving conditions. Changing it every 3K mi. is a waste of money and oil.
And while we’re at it, has anybody heard about changing the oil in a new car at 1K mi. just to get out any machining chips? Is there any validity to that one?
scr4, that’s not the way it works. The engine is not immersed in oil. The oil just collects by gravity (or, according to other theories, by its own weight) in the sump pan. The oil pump takes it from there and pumps it to all the places that need lubrication (like bearings and such) and after it exits it drips back into the sump. If the oil pump is not working the oil in there is pretty much useless.
BTW, I have a really advanced car and have not needed to change the oil in many tens of thousands of miles. When it was new it needed oil changes but after if passed 100K miles it stopped needing oil changes.
I change mine in my Mustang every 3000 miles or whenever I get bored, whichever comes first. Do you have any cites for it being a waste of money and oil? Sure, there is a definite diminishing return, but to say it is just a waste is not necessarily correct.
Also, time is another factor. I think a standard recommendation is to change it every 6 months regardless of miles.
This has been argued at length, but I’m not sure there is a total consensus. I’m a MechEng who has rebuilt many engines from scratch, and seen what is left over in the machining process, and knows how much metal falls out in the wear-polishing process. As a result, this lady is going to change at 1000 miles, thank you.
Sailor, I caught that! I used to have one like that too;
just add a quart every 1200 miles and keep on rollin’.
Engines have been made that use sealed bearings for all of the rotating wear surfaces. I have an RC airplane 2-stroke that has a crankshaft mounted on roller bearings. These in general don’t work in automotive applications due to two things - they only work for lower-stress applications, and their longevity is not nearly as good as an oil-pressure fed journal bearing. Part of this is due to the heat of the engine - the bearings would need to be cooled by some non-corrosive medium - like oil. And if you are circulating oil for cooling, then you probably ought to be using journal bearings to begin with.
Anthracite, I’ll cite my '95 Mustang V-6, and its owner’s manual. It has 147,000 miles and has never missed a lick.
I have the oil changed every 6000 miles.
Good night
Well, that wasn’t what I asked at all. But since we’re citing manuals, I’ll cite my 98 Mustang GT’s (4.6 V8!) Maintenance manual, ID number F8ZJ-19T200-AA, severe duty schedule (my driving habits qualify under their definition) pages 22-38:
Every 3000 miles “replace engine oil and replace oil filter”.
Sleep tight, V6 boy. 
Una, the V8 gal.
Yes, oil and antifreeze have anticorrosives and other additives that decay with time and it is recommended to change them at least every year even if they have not done their limit in miles/hours. But I am too lazy to do it. My boat has a 3 cylinder diesel that in the last few seasons has hardly run. Changing the oil is a pain (you can’t get under the motor) and it has gallons of antifreeze… forget it.
Thanks for the responses everyone. I never add oil to my car and just wondered how long it would keep on running without it. The last time I put oil in it was last year or the year before I think-
Debbie
Without sounding too melodramatic Debbie, it really sounds like you are driving on borrowed time. Which is sad if true - oil changes and checking your level and adding oil are relatively little expense and hassle relative to having to buy a new engine, or a new car.
It is possible if you have a really god car (like a 1990’s Japanese car) that doesn’t burn hardly any oil that you may not have run low. In this case, you should have the oil changed immediately, and commence regular checking of the oil and adding it. Your car will have suffered some reduced life - how much, no one can know.
Running out of oil completely is bad - you’ll be driving along at night in a bad neighboorhood, and notice that you need to press harder and harder on the gas to keep going. There may be a little red light on your dash telling you doom is approaching, but these often do not work. Then, finally, the engine will cough and die, and will never start again. And you get to ask the nearest gang-banger if you borrow his flip phone to call for a tow.
Please do something about your poor car immediately.
As one who has had an engine seize up from lack of oil, I can assure you that you do need to keep up on that sort of thing.
Fortunately for me, I was a block from a 7-11. I put in 3 quarts and I was back in business.
(That VW Rabbit probably hated me. :D)
I’m not an expert, but this is kind of scary. Have you ever looked at your oil? Ever felt new vs. used motor oil? Obviously lubrication is a big deal, but if that were the only issue, the only reason you’d change it would be for viscosity breakdown. Nobody’s mentioned the real reason you change your oil–the dirt. If you keep accumulating dirt in your oil, it will cause excessive wear, and will eventually cause the oil to become sticky. This can and will damage your engine.
This is a little messy but do it and you will understand a little better. Take a quart of new oil, dip your finger in it, and rub it between your fingers. Then take some well-used oil off the end of your dipstick and rub it between your fingers. (Better yet, feel it after you’ve drained it from the oil pan.) You will feel the grit that builds up in your engine. Why? Because your car uses outside air mixed with gas and burns it. You are going to get dirt that the air filter misses and also from the partially unburnt fuel.
I’d agree, but I doubt you’d be able to seal it as cost-effectively as just using oil. A mechanical engineer would be better able to answer the question, but if you change the oil & filter every 4000 miles, after 100K you’ve probably only spent $250. ($1.50/qt * 5 qt + $2.50 for filter) Of course you’ll pay twice as much to have someone else do it for you. Still, it’s likely to be cheaper (and last longer) than all the extra parts you’re talking about. Gaskets and seals seem to go out more often than pistons, cams, and crankshafts, at least in a properly maintained vehicle.
Okay, now I’m scared! I’m going to get some oil in it TODAY. It’s a Subaru btw, and it’s been ticking like a VW Beetle. Someone told me the ticking was from lack of oil, or I needed heavy weight oil.
Debbie
IIRC, ticking can be caused by worn engine parts (esp. lifters) as they slop around a bit.
If you change your oil, make sure you change the filter too. And if your air filter is dirty, it’s a good idea to change that as well.