Lower Unit Oil

[zippy83]

Hello all,

I was wondering what type of lower unit oil should I use when I get ready to change my lower unit oil?
I have a older 1973 Mercury 50HP outboard. I am also wondering where I can get some seals for the two bolts..

Thank you
Zipp

 

[JimS123]

Re: Lower Unit Oil

Regular 90 weight marine gearcase oil. Any Merc dealer will have the washers.

 

[zippy83]

Re: Lower Unit Oil

I will find one in my area and get that taken care off
Thanks JimS123

 

[zippy83]

Re: Lower Unit Oil

hello again,

Just got back from the Mercury dealer. They told me to use the following SEA 80W-90. They said I "should be good" with this bottle.
I also released the bad oil from the lower unit. Since this is my firs time doing this I was told here on another thread to look for moisture and water. Im not sure how to determine that. I have attached a few pictures maybe someone can tell me if this is clean or not.




Also when I took the first screw out from the bottom, almost nothing came out only when I released the upper screw that is when it slowly started to come out. It was thick but at the same time its only 19F outside (35F in the garage) and the outboard was cold. It took about good 20 min until it stopped dripping. I have not put the new oil in yet.

Thanks
Zipp

 

[tazrig]

Re: Lower Unit Oil

Zipp that oil looks fine. This is what milky oil looks like:



Next time you might want to bring the engine in the house or basement and let it warm up over night before draining it. It will drain out much faster for you when warm. Same goes for refilling.

 

[JimS123]

Re: Lower Unit Oil

Bad Fall weather and the hunting season got the best of me too this year. I didn't get to winterize 2 of my boats (both outboards) until black Friday (temp was 25 in the garage). It did drain slow, but I had the new tubes warmed up in the house first and they went in just fine.

Your pic looks like dirty oil (normal). If its got water in it you won't have a problem distinguishing milky oil.

 

[zippy83]

Re: Lower Unit Oil

Thanks tazrig and Jim

I will keep that in mind next time. I guess for now I can keep the new oil inside the house for a day and then change it out.

 

[tazrig]

Re: Lower Unit Oil

Thanks tazrig and Jim

I will keep that in mind next time. I guess for now I can keep the new oil inside the house for a day and then change it out.

Sounds like a plan. Good luck Zipp:thumb:

 

[zippy83]

Re: Lower Unit Oil

Sooo changed the oil last Saturday. I did it as instructed. Removed lower screw, removed upper screw... waited 30 min for the old oil to drain, went to the store got a pump, oil, and washers. pumped the new oil untill it started to leak out of the top hole, put the top screw in, removed the pump... put the bottom screw in.. wiped the lower unit and that was it. Yesterday I was in the garage and was lookin at it to make sure the bolts are not leaking and it was all good. Tonight I was getting some stuff and noticed that I had some oil leak, from what I was able to tell it was comming from the prop area. The oil looked dirty nothing I put in recently. I know usually when it runns you get that exhaust junk to come out, but it hasnt been running since October. However since I drained the oil it has been tilted down all the way... but again it has been tilted down for the last 5-6 days or so. I have attached a picture and put a spark plug next to it so that it can be seen how much came out.



Any idea what this could be?
Thanks
Zipp

 

[dingbat]

Re: Lower Unit Oil

Sooo changed the oil last Saturday. I did it as instructed. Removed lower screw, removed upper screw... waited 30 min for the old oil to drain, went to the store got a pump, oil, and washers. pumped the new oil untill it started to leak out of the top hole, put the top screw in, removed the pump... put the bottom screw in.. wiped the lower unit and that was it. Yesterday I was in the garage and was lookin at it to make sure the bolts are not leaking and it was all good. Tonight I was getting some stuff and noticed that I had some oil leak, from what I was able to tell it was comming from the prop area. The oil looked dirty nothing I put in recently. I know usually when it runns you get that exhaust junk to come out, but it hasnt been running since October. However since I drained the oil it has been tilted down all the way... but again it has been tilted down for the last 5-6 days or so. I have attached a picture and put a spark plug next to it so that it can be seen how much came out.

View attachment 219210

Any idea what this could be?
Thanks
Zipp

Looks like spent fuel / carbon build-up draining out of the leg (exhaust) . Pretty normal if a motor idles or run at low RPM or any length of time.

 

[robert graham]

Re: Lower Unit Oil

I wouldn't worry about that little bit of oil...probably just from the exhaust....

 

[zippy83]

Re: Lower Unit Oil

I wouldn't worry about that little bit of oil...probably just from the exhaust....

It does seem dirty and I just went out with a flash light and poked around the prop and there is some dirty oil/exhaust still in there.

 

[dingbat]

Re: Lower Unit Oil

It does seem dirty and I just went out with a flash light and poked around the prop and there is some dirty oil/exhaust still in there.

Does it look like fogging oil? :laugh:

The whole inside of your block is covered with that oil and fuel mixture. So much so that's dripping from inside the block, thru the exhaust and out on your floor. It's what lubricates the bearing an journals and the reason why I said 2 strokes are self fogging.

 

[tazrig]

Re: Lower Unit Oil

It does seem dirty and I just went out with a flash light and poked around the prop and there is some dirty oil/exhaust still in there.

Bottom line Zip, nothing to worry about. If you took an eye dropper and put 2 drops of oil or gas on concrete it would spread out further than that. If a cup of the stuff landed on the floor you might have something to worry about but you are fine. Trust me on this one.

 

[Home Cookin']

Re: Lower Unit Oil

looks like you got it down. I take it you haven't done it twice since your first post?

on a larger motor and if the equipment isn't right you can end up with the driveway looking like the Valdez, especially with a breeze. I learned to put down a pizza box to work over.

 

[Sea Rider]

Re: Lower Unit Oil

Zippy,

When you drain very filthy gear oil, with lube pump squeeze 1/4 bottle new oil gear through upper plug, rotate prop while doing so to wash all filthy oil leftovers with new oil. Lower bolt must be reemoved in order to pump through upper plug. Once all oil is drained on a pan can fill entire gear case with new oil as you been doing. Change oil each 100 worked hours.

Happy Boating

 

[zippy83]

Re: Lower Unit Oil

Does it look like fogging oil? :laugh:

The whole inside of your block is covered with that oil and fuel mixture. So much so that's dripping from inside the block, thru the exhaust and out on your floor. It's what lubricates the bearing an journals and the reason why I said 2 strokes are self fogging.

Could be it started to drip after I fogged the cylinders..

 

[zippy83]

Re: Lower Unit Oil

Bottom line Zip, nothing to worry about. If you took an eye dropper and put 2 drops of oil or gas on concrete it would spread out further than that. If a cup of the stuff landed on the floor you might have something to worry about but you are fine. Trust me on this one.

I aree.. Since then I had one more dropp LOL.. Could be the fogging oil as dingbat said

 

[zippy83]

Re: Lower Unit Oil

Zippy,

When you drain very filthy gear oil, with lube pump squeeze 1/4 bottle new oil gear through upper plug, rotate prop while doing so to wash all filthy oil leftovers with new oil. Lower bolt must be reemoved in order to pump through upper plug. Once all oil is drained on a pan can fill entire gear case with new oil as you been doing. Change oil each 100 worked hours.

Happy Boating

Actually this sounds like a good idea... I may end up changing the lower unit oil again to practice some more

 

[dingbat]

Re: Lower Unit Oil

The proper way to change gear oil is when the LU is still warm. The oil flows a lot easier minimizing retained fluid the particles are still suspended in the fluid instead of falling out of suspension and collecting in recesses and such that don't drain when the fluids are cold. Make sure you have a magnetic drain plug as well.

If the inside of your LU is that dirty, fill it up and run it for a couple of days before changing it again. Once clean it will stay that way unless you have mechanical tolerance issues or the fluid is contaminated. I change my LU oil every October. Most years there is still a tinge of green left in the oil even after 200-250 hours of use