> It's astonishing the quantity of people that rarely (or never) do oil changes on their cars. And I don't mean by themselves, but just bringing it to a workshop. And that's the easiest and most effective way to keep your car running longer in most of the world.
Case in point: several years ago my wife's car died while we were on a trip (fortunately we were close enough to home that we could get a ride back from family and have the car towed). When I took the car to the shop to fix, they informed me that the engine had seized, and that the most likely cause was that the oil hadn't been changed for too long. When I asked my wife when the last time was that she had changed the oil in her car, she said "I'm not sure but I think it was before we got married". That meant it had been at least 5 years since the oil was changed in that car!
I have always changed the oil in my car reasonably regularly (every 3000 miles, or whatever the oil is rated for). I never knew why, that was just what I was taught about how to maintain a car. My wife obviously didn't get that lesson from her parents (or didn't listen), and unfortunately the neglect of maintenance killed her car.
Modern synthetic oils run in circles around the ones my dad used, and can easily get 7-10K miles. But it will also depend on the temperature of your engine (higher temp, less life). And also contaminants. If some humidity or coolant filters to your oil because of a bad gasket or because of bad combustion, after some time the oil can become a sludge and seize your engine.
So it's a good to change oil every so often even if you don't do a lot of mileage. A year and a half or two might be OK (unless you're doing tens of thousands of miles a year), but five years... over the top, I think.
I just expend 150 a year on the yearly maintenance (oil and filter change, air filter, some other stuff...) and forget about it.
(Mind my English, not my first language and I might be butchering the car terminology)