I can tell you from personal experience that after only changing the oil in a car every 10 to 15 thousand miles... that car lasted me for nearly 20 years... after which I sold it. It still ran perfectly. If the oil isn't low... you can keep going for many many more miles than 3000. The oil companies don't want you to know that, though.
It should definitely be changed now and then, but every 3000 miles is far more often than necessary. Just check the levels to make sure it has enough.
It should definitely be changed now and then, but every 3000 miles is far more often than necessary. Just check the levels to make sure it has enough.