New boat to me .. sucked out all the oil as usual and put in 2 more quarts then I needed after texting the previous owner.
Sucked out 2 quarts, expected clean oil ... it was still dark and old.
What`s up with that ?
I stopped at 2 quarts but now I`m thinking keep sucking teh oil out till I get clean oil .
I took off the oil filter after I sucked the oil out...

Your new clean oil if mixed with sediment or a little old oil would likely have a streak type look with the dirty oil mixed into the clean. Fluid film won't mix unless agitated.

Maybe pit a new filter on and run it, see what the oil looks like on the dip stick? Make the call then?

My Cummins, when I change oil using a stratapore filter, the new oil is clean after running up, even in a diesel and likely had old oil left in the pan.

Nice clean engine setup on the Cat.

Oil coolers always hold some

Part of the reason why i installed the long hose drain plug kit. Warm up the engines, unscrew oil filter and let it drain for 15 min, and let the pan drains empty with the dirty stuff. Add new oil, dipstick always super clean and clear.
but yes, oil coolers and few hoses dont drain completly empty...

The long hose ? So gravity drained , out the drain plug ?
Id prefer to do that and i have lot of room under the engine actually and all accessible. I like this.

I agree I love the drain plug hose way of doing it. I just push the hose out the drainplug hole and have a catch pan under the boat. So easy and it drains it as complete as you can get.

Also makes it easy to get a good oil sample. Just wait until about half the oil is drained and take the sample.

I put a hose kit on when had engine out to do coupler. They drain slow because the hose has to be small enough to fit through plug hole. I always drain it overnight.

I do the drain plug kit as well but brought the hose up and have a hydraulic quick disconnect fitting. Warm the motors, my oil filters are upside down so punch a hole and let them drain then hook a pump up. I only have 8 QTS, takes about 10 min per motor.

After adding oil and even after a few runs mine still look clean.

yes exact, less work than vacuum it out leaving the crap in the bottom of pan imo...

Here you go:

Mercury-Mercruiser 32-865281A02 Oil Drain Hose Kit 38" Genuine factory part (mercruiserparts.com)