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  1. #1

    Default oil/water mix leakage from bottom of leg

    I have a merc model 850 outboard motor, when I fired it up in a barrel of water for first time it left a dark oil spotty film and from what I could see it was coming from around the prop where it usually drained a little water from in the past but never noticed oil before, this looks like a water oil mix, not creamy or grey but darker, something to be concerned about? when I opened the oil plug on leg there was no oil or water draining but there was oil in it but maybe low, which brings in to question what is the best oil to use, I used ordinary motor oil last year 10-30. compression test 119-119-115-120? still good?

  2. #2
    Join Date
    Sep 2010

    Default Re: oil/water mix leakage from bottom of leg

    ??---------The lower unit takes a marine grade OUTBOARD GEAR OIL.-------The oil you mix with the gas is TCW-3 oil.------------Fill gearcase from the BOTTOM till it comes out the top.------------I would say you have been lucky so far.----------Maybe invest in a lottery ticket today.

  3. #3
    Join Date
    Apr 2016
    barnegat NJ

    Default Re: oil/water mix leakage from bottom of leg

    That's unburned fuel and oil mixture in your tank,normal

  4. #4
    Join Date
    Dec 2015
    maplevalley WA

    Default Re: oil/water mix leakage from bottom of leg

    Definately completely drain the gearbox 10W30 motor oil will just foam up instantly with high speed gears in the gearbox. Get a hypoid outboard specific gear oil and get enough for at least two oil changes. Fill it like above and run it for a bit then change it again that should get rid of the crap in there. Does the black oil smell like fuel? Once you get the proper gearoil in the lower unit it is real easy to tell the difference by smell. If it smells like gearoil you need to reseal the lower unit.

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