How much neglect do you need to get a car's engine and transmission to fail? Even if you didn't change the engine and transmission oil for 18 months that would

How much neglect do you need to get a car's engine and transmission to fail? Even if you didn't change the engine and transmission oil for 18 months that wouldn't happen. I bet it wouldn't happen if you didn't change it for 24 months. Compare and contrast with not plugging in a car for < 4 weeks.