What is this fluid reservoir on my 4.3 MPI?

[Jimwhall]

I'm getting to know my '16 Four Winns with the 4.3 MPI. So far I love it. It's so much bigger than my 16' Sylvan, and the 4.3 has all the power I could want (I was worried I'd be missing a V8 in a bigger boat). I ordered some manuals online, and am trying to get to know the engine and hull, but yesterday when I was peeking about I saw a reservoir in the back of the boat, on the side of the engine behind the battery that I couldn't identify. I've looked online but not found anything. It's about half full of fluid. On the front of the engine I can see that there is a gear lube reservoir, and the oil is in the engine (do marine engines have an oil pan???). But this guy to the right I had no idea what it might be. It's towards the transom so maybe it's power steering?

I just want to know so I know what to add when the time comes.

Thank you for any help!

 

[GA_Boater]

Oil pans - Yes.

That appears to be the tilt and trim pump.

 

[Stinnett21]

Yep trim pump. Raises/lowers your outdrive.

 

[racerone]

Have your assistant operate the trim / tilt switch and see if motor on that unit operates.