Driveline oil resevoir

[starcrafter]

I am at work and forgot to look up in my owner's manual what the driveline oil resevoir is for and what oil goes in it. It is on a 2001 5.7 mercruiser and it sits on top of the motor on the right side as your looking at the front. I am wondering if is the same oil used in the lower unit or is this for a transmission type function?<br />Also, what is recommended for the lower unit oil?<br />Thanks in advance for your help.