I had the same problem on my 99 S80. Talk about poor quality. I've never heard of a dip stick fall apart like this in any other car. There are likely many other S80s with this problem. What ticks me off is not only the poor quality, obviously not designed for the temperature and stresses; but especially that the solution is to replace the tube also.

I bought the new dip stick only. Using the old stick carefully insert it down the tube if your plastic (the weak link) will push it down to the right stop point. Do this to confirm the oil level is high or low on the old stick. (Pull it out with needlenose if the plastic separates from the stick. Then insert the new stick. Mark the position for the oil level and find the high and low level from the old stick by placing the old and new stick side by side with the oil level aligned. Mark the high and low marks from the old on the new stick. It may look tacky but it works.

GR