Oil Sheen in the water... normal?

This is our first year with our new to us boat, so I'm still trying to learn what's normal and what's not. Yesterday was the first time I've ever been right at the back of the boat when we cut the engine (changing tubers) when I noticed a slight oil sheen around the outdrive. It disapated in less then a minute, so I don't know if it's always done that or not. We pulled the boat from the water and everything looks good. Fluids are full, nothing is "milky" looking, and we don't see any fluids leaking. Of course we'll check under the boat again when we go back next time and make sure nothing "puddled" on the ground. We've been out almost every weekend this summer and the only fluid we've had to add was drive oil because the reservior was low, but we figured we've really been using the heck out of the boat, so we didn't think twice about it. Now, just for the record I'm the paranoid wife who always thinks there is something wrong with the boat, even though it's been great to us so far (knocking on wood, sure I jinxed us)...

Should we be concerned? Could this be normal?

Re: Oil Sheen in the water... normal?

Ayuh,.... While it's possible your seeing the sheen from unburnt gas, the drive should never need Refilling, except when serviced...

Re: Oil Sheen in the water... normal?

Sounds like a leaking trim cylinder if you're having to refill the reservoir.

Re: Oil Sheen in the water... normal?

Desera,
That sheen usually comes from one of five sources:

(1) Un-burnt fuel in the exhaust.
(2) Gear oil leaking from the outdrive.
(3) Motor oil from worn engine components.
(4) Hydraulic oil from the trim system.
(5) Petroleum residue from bilge water.

Per your description, I am suspecting a leak in the outdrive as this is the system requiring topping the fluid.
Have the unit pressure tested and corrective action taken.

Re: Oil Sheen in the water... normal?

Per your description, I am suspecting a leak in the outdrive as this is the system requiring topping the fluid.
Have the unit pressure tested and corrective action taken.

Click to expand...

that's where i'd be at too. the drive is a sealed unit that isn't supposed to use any fluid. if it is, it must be escaping from some where..

Re: Oil Sheen in the water... normal?

If your drive is low its because you have a leak or it wan't filled to the max when changed. If the level stays the same after checking it a couple of more times after use its probably the latter.

All the answers to this post were very good - esp eddiepetty

I get a gas sheen from my middle engine just from stepping on the boat (like today), and it comes from the exhaust - as the prop from my middle engine sinks just barely into water.

Difference between gas sheen and oil sheen is there will be some brown color with the oil sheen.

I have a tilt that leaks a little, and it throws red tranny fluid when the tilt is turned on.

Common stuff with outboards.

Yamaha F225s at 50MPH https://vimeo.com/268705607#

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