One thing the oil change places do is suggest every 3 months. Oil lasts for
years on the shelf. It doesn't degrade much just by sitting in the oil pan,
so I think this 3-month thing is bogus, unless there are only short trips
and a lot of them.
A lot of cars do give computer-generated reminders. It is called the change
oil soon light. There are also other indicators, like the indicator that
says how many miles your oil is good for.
You can also buy a kit that pumps oil into the crankcase very slowly. And it
pumps used oil into the diesel tank, also very slowly. This way, all you
have to do is change the oil filter and refill the oil. But there is never a
need to drain the oil. AFIK, this is available only for big trucks. I
suspect it would work just fine in cars, too.
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