Old men married to young wives...

The marriage of an 80 year old man and a 20 year old woman was the talk of the town.
After being married a year, the couple went to the hospital for the birth of their first child.
The attending nurse came out of the delivery room to congratulate the old gentleman and said, 'This is amazing.
How do you do it at your age?'
The old man grinned and said, 'You got to keep the old motor running.
The following year, the couple returned to the hospital for the birth of their second child.
The same nurse was attending the delivery and again went out to congratulate the old man who just grinned and said,
'You gotta keep the old motor running.'
A year later, the couple returned to the hospital for the birth of their third child.
The same nurse was there for this birth also and, after the delivery, she once again approached the old gentleman, smiled, and said, well, how did you do that?
It's like I've told you before, you gotta keep the old motor running.'
The nurse, still smiling, patted him on the back and said: 'Well, I guess it's time to change the oil. This one's black.'