Is it bad to put 10K miles oil in a really old car? corolla 1990?

Your question makes no sense. What is 10k miles oil?

A 1990 Corolla isn't a 'really old car' - that's still new for a Corolla because they live forever. I have an '85 Corolla and it never stops and in 15 years I've never had to have major repairs done. We have another newer car as well and have spent a lot more on it. My mum has a '75 Corolla van (it runs in the family) and she has people follow her and ask to buy it.
No idea what you're talking about with the oil but please treat your Corolla with respect!

I suspect the question is whether it is okay to reuse motor oil that has been run in a different car for 10,000 miles. If so, it isn't. If it came from a car in perfect condition, it might have been clean enough when it came out. The process of draining the oil and getting it into another container would surely have contaminated it badly. New oil can't possibly be that expensive.

Nothing wrong with putting an oil rated for 10K miles between changes into an older car such as the 1990 Corolla, but I would not try to get 10K miles out of it because an older engine with a lot of wear will contaminate the oil more quickly.

That's what it sounds like at first but not what the person is asking. What he's asking is whether it makes sense to put oil rated not to break down in 10K miles in an old car.

Normally you want a slightly heavier oil in older engines.

We can't answer this question because it also depends on what kind of driving you do mostly? Mostly highway or city driving? It also depends on if you choose to buy the cheapest oil, oil filters, and skimp on the rest of the car engine maintenance.

If you treat you car with loving care and try not to be the cheapest person in the world like using homemade oil filters made from used toilet paper rolls and such then maybe you can stretch out the oil changes to this extreme.

If you want to do this on a regular basis and still not buy the premium replacement products, I don't think you are doing your car a service.

If it was a one time fluke where time and distance just snuck up on you and you realized that 10000 miles has passed since the last oil change you're probably fine to let it happen just once.

Either way, don't be a cheapo. A car is a necessary investment if you live where there isn't a viable public transportation system. If you insist on doing everything on the ubercheap? You're gambling with the engine's life....

Here is one oil manufacturer's suite of long- life (synthetic) oils for a 1990 Toyota Corolla.

http://www.amsoil.com/mygarage/vehiclelookup.aspx?url2=1990+TOYOTA+COROLLA+C

Clearly, I missed the thrust of the op.

While getting my car serviced at the Ford Quick Lane, I wandered the showroom, and hoo - boy! Something called a Fiesta showcased at $23.000! Taurus over $32,000. Of course, those in the showroom are at the high option of each model, but yeah, maintenance is getting even more important.

If what you are asking is whether or not synthetic oil (for example Mobil 1) can be used in an older car....the answer is yes. Both the mfr of Mobil1 and other synthetic oil mfr as well as independent labs have stated that it can used with no problem.

However used oil should not be re-used. That makes no economic sense.

Why not clarify your question?

Im sorry to not be clear with my question,
The regular car oil is changed every 3K -5Kmiles. There r oil which can be change every 10K miles. Im using the 10k miles oil so that I can reduce the number of times I change oil in a year. Is this bad for a old corolla 1990?

As was stated prior, synthetic oil (such as Mobil 1) is just fine for older cars as well as newer cars.

However, there is more to maintenance than just doing regular oil changes. It would depend on how well the rest of the proper maintenance of the vehicle has been for the life of the car. Basically, if it has been properly maintained (gaskets, main seals, valves and reg tune-ups), the car should be fine with a properly engineered synthetic oil. If the car hasn't been properly maintained, it won't resurrect a wreck or a car that has been badly treated.

Personally I use reg oil in my car as it is cheaper. I change the oil regularly with a high quality filter, and save my money for other things. I see no big advantage. I do use an additive that reduces friction about 10k miles per year. It works out to about the same effect.

You do realize that what synthetic oil is composed of is a mixture of fossil-derived petroleum products and synthetic additives.

Another view of the thing...

The full synthetic oil does not break down. I HAVE seen a couple of cases where a guy would never change it at all, i.e. he'd just change filters every 4000 miles or so and top off the oil when it was a bit low. I've seen one car which had been treated like that from new to 150,000 miles and which ran nicely. I use full synthetic and change it when it gets too dirty for me to stand looking at, which is usually around 5,000 miles.

With that clarification, my answer is that 10,000 k oil is fine, but as someone mentioned earlier, that doesn't mean it can run for 10,000. It may not break down, but as Gunga mentions, it does get dirty. When it gets dirty, change it. In the nature of old, high mileage engines, it might well get dirty long before you get any benefit from the superior oil.