How to change the gearcase oil?

[Kuba]

2008 50hp 2 stroke Mercury, im planning on going out tommorow, if the crazy marine forecast calls off 2 meter waves ;P

Anyway, anything to it when changing the oil? remove both plugs, drain..... put the bottom one, fill the top to the top....?

[lineman49]

  If you are doing the lower gear case, drain out, fill from the bottom hole up to the top hole, replace the top plug first & then the replace bottom plug. clean up mess!

[Kuba]

Why not fill from top??????

[steelydan]

you will not get enough gear oil in from the top. air will get trapped.

Edited April 23, 2013 by steelydan

[Tim Bromund]

filling from the bottom ensures there are no air bubbles trapped in the drive.

[Willy-C]

Kuba,

 

I always change my L/U oil in the fall when I'm winterizing......because gravity will let any contaminates settle over the winter and collect internally in the housing, and if there's any water intrusion you'll see it before freezing temps damage it from expansion...... if you spot  issues you won't be pressured to fix it in the spring, you could work on it during the winter months 

[Kuba]

Willy, I know. Someone told me yesterday why it should be changed in the fall and not in the spring. My garage is attatched to the house and is somewhat insulated. Temp. In there does not go below 0, and i never had anything freeze inside - keep all my bottled water in there.

Anyway, hopefully there will be no rust in there. I'll find out in few hours.

[LongLine]

Make sure you take out the right screws!  Get yourself one of those quart bottle pumps that screws into the bottom one.  Pump till oil comes out the top hole.  Wait a few seconds then give it another slow pump.  Put in the top screw with a new gasket/washer, unscrew pump hose from bottom hole & put in screw - also with new gasket/washer.

 

Make sure you get the old gasket/washers off. (sometimes they stick to the hole)

 

Tom B.

(LongLine)

[Willy-C]

O?.........Ooops, I see you're in Canada......water freezes in colder temps up there....  ....(Celsius  )

 

Good Luck