Any advice on gear oil on a mercruiser

[rafiki_]

The drive was (boat now sold) a Bravo I XR, mated to a 496HO, and at the time I took the pics it was 3 years old but with only 100 hours or so.
Mind, other than the muddy deposit, the oil actually looked pretty good, not milky at all, and I didn't find any metallic bits when I changed it, so I can't say it didn't do its job.
But surely the bottle bottom did look scary.

Interesting, so for you this was muck coming out of the Quicksilver oil?

 

[MapisM]

Always after the first run out the bottle will have lost 5mm ish of fluid, but then once topped up stays still.

I've never lost a lot of fluid and the alarm has never gone off. What else would you suggest to make sure the fill is fully done with all air expelled??

Well, I wouldn't worry for a few millimiters drop after the refill.
While I said that I didn't have to top it after refill, I couldn't swear that the level didn't change just a little bit. What I'm sure of is that I filled it to its max level, and it never went below the min afterwards.
It actually went slightly above max after running the boat hard, obviously due to heat expansion, but I'm talking of trivial differences anyway.

I'm not aware of any reliable way to be sure of not leaving air bubble inside, but I think the risk is negligible if refilled properly. I would just suggest to:
1) warm the drive before emptying it, and leave it draining for as long as you can (I had it run at WOT for a while just before lifting the boat, opened it immediately and left it to drain overnight);
2) check that upon refill you pump exactly the amount which is supposed to fill the drive (I previously said 3 liters by heart, but better check the exact quantity).

 

[MapisM]

Interesting, so for you this was muck coming out of the Quicksilver oil?

Absolutely, also because that was exactly the same thing which I found described in offshoreonly forum, which is where I understood also of the "green death" nickname...
I've not been on that forum a lot since I sold the boat, but you might find some references if you wish to google for that.

 

[paultallett]

Well, I wouldn't worry for a few millimiters drop after the refill.
While I said that I didn't have to top it after refill, I couldn't swear that the level didn't change just a little bit. What I'm sure of is that I filled it to its max level, and it never went below the min afterwards.
It actually went slightly above max after running the boat hard, obviously due to heat expansion, but I'm talking of trivial differences anyway.

I'm not aware of any reliable way to be sure of not leaving air bubble inside, but I think the risk is negligible if refilled properly. I would just suggest to:
1) warm the drive before emptying it, and leave it draining for as long as you can (I had it run at WOT for a while just before lifting the boat, opened it immediately and left it to drain overnight);
2) check that upon refill you pump exactly the amount which is supposed to fill the drive (I previously said 3 liters by heart, but better check the exact quantity).

Great.... That confirms exactly how I find mine