I just discovered that the oil capacity for our engines is 5 quarts.

When changing your oil and filter, only 4 quarts drain out.

If the engine is split open and torn down, the last quart of oil will come out. A dry engine will require 5 quarts.

This means that every time you do an oil change, the motor ends up having 20% of old oil still inside of it.

Interesting bit of information. Regardless of the fact, Honda has designed these engines and created the maintenance schedule with this in mind.