This is what we call an "old father's tale."
When I was learning to drive a car, my father told me that it's better for the car if the engine is turned off while the car is in neutral instead of park. After it's turned off, he said to shift it into park. After fifteen years, I still do this, even though my husband insists it makes no difference. Who's right?
TOM: There's something you must understand about fathers, Jill. In the eyes of their daughters, they need to come across as wise and all-knowing. They feel constant pressure to impart great, unyielding truths to their daughters. Of course, given this pressure, they tend to make things up a lot.
RAY: And you're practicing what we call an "old father's tale." I can take a guess at what he was thinking. When you shift from drive to park, the shift lever passes briefly through neutral and reverse. Theoretically, you're making three rapid shifts; one from drive to neutral, one from neutral to reverse, and one from reverse to park. He was thinking that those quick shifts put unnecessary wear and tear on the drive train.
TOM: But in reality, the transmission never has time to shift into neutral or reverse on its way to park. It takes the transmission a moment to respond to your selection. So unless you stop for a cup of coffee and a donut in each gear, you won't do any damage. If you move the shift lever reasonably quickly (what we call in the trade "zonking it in"), you eliminate any need to practice your father's approach.
RAY: There is, of course, no need to ever tell your father or your husband who's correct. Giving your husband the smug satisfaction of knowing he's been right all these years is obviously out of the questions. And telling your poor father that he's wrong will only hurt his feelings, and might even cause him to write you out of the will!