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  1. #1
    Member
    Join Date
    Jul 2008
    Location
    Toronto
    Posts
    227

    2001 150 EFI SN OT273684 lower unit

    I normally change the bottom end oil each fall, at the conclusion of the season. The boat didn't get a lot of use last year so i didn't bother changing the bottom end oil. I drained it this fall and the first thing that came out was maybe half a thimble full of clear water. If i hadn't of been watching i doubt i would have noticed it. After that it was oil, with no discolouration as i use synthetic and it will not mix. I use Royal Purple, and have been for years now.
    My thought is to run it next season and keep an eye on it. Does that sound like a reasonable thought process?
    Thanks

  2. Member
    Join Date
    Jul 2018
    Location
    Flint Michigan
    Posts
    399
    #2
    Most likely condensation from sitting so long.
    I'd run it a few times....then do another fluid change.
    Most likely be fine.
    1994 SWIFT boat 200-SDX
    1999 Mercury EFI 150

  3. Mercury 3L/4 Stroke/Verado Moderator EuropeanAM's Avatar
    Join Date
    Apr 2008
    Location
    Greenville, SC (US)
    Posts
    94,945
    #3
    What did the drain plug seals look like?

    Suggest those be replaced, at a minimum (pressure test also wise). Easy to do while gearcase is off for your annual Water Pump.

    Did you know: Mercury High Performance Lube is a full synthetic lube, with fluid emulsifiers to help protect the gearcase if or when water enters it?


    Dual Mercury Master Technician- for Mercury Outboards, Mercruiser and Mercury Racing at European Marine in Greenville, SC.
    Still consider myself a "Marine Apprentice" after 47 years (learn something new every day).
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