Is smell of lower unit oil normal?

[hkeiner]

While winterizing my 150hp outboard for the winter, I noticed that the old oil I drained from the lower unit had a somewhat strong unpleasant smell. It was kind of like the smell of an open sewer or septic tank. Is this normal? Can this be caused by water leaking into the lower unit oil, mixing with the oil, and then turning foul? The new replaceement oil did not smell like this. Both the new and old oil are Mercury brand.

The old drained oil looked OK to me visually, I guess. It was dark in color, not "milky" looking, and there was no water separated from the oil. The motor sat unused for over one month before I drained the oil, so I expect that any water mixed in with the oil would have separated out and have been visible after draining it into a container

It is not the smell itself that bothers me, of course, but the chance that water is getting into the lower unit, which may cause damage over time.

Thanks in advance for any thoughts on this.

 

[Paul DuLaney]

Re: Is smell of lower unit oil normal?

I noticed this myself on my 150efi and I think it's the merc oil it my self. Main thing is no water in unit and to level it when you change it.I put a small level on side of the unit and trim it until level and add oil slowly.

 

[Laddies]

Re: Is smell of lower unit oil normal?

The lube is burned a little and thats a normal smell.

 

[hkeiner]

Re: Is smell of lower unit oil normal?

Thanks for the replies. Now I know not to worry...