blue streaks in drained lower unit oil

[MC Degner]

I just drained the lower unit oil on my 90 hp Johnson, and about half of it was tinted blue. Why is this? And, is it a problem? (The rest was pure and golden, like me )

 

[ob]

Re: blue streaks in drained lower unit oil

Never heard that one before.Was the half that was blue the first or second half that drained out or just distributed throughout? As in perhaps there were two different incompatible gear oils put in at one time that had separated.Otherwise insure that you're not looking at water emulsification that has separated from the oil that may containg some oxidized content that turned that color.Only metal however I am familiar with that would produce such a color when oxidized is copper or brass.

 

[Brew2]

Re: blue streaks in drained lower unit oil

I'm with OB. Two different gear oils used.

Many of the gear lubes are now blue instead of golden. Is this a relatively new motor to you? Perhaps the previous owner used blue gear lube?

 

[MC Degner]

Re: blue streaks in drained lower unit oil

Relatively new, yes. But I resealed the LU last summer and have put in Lubrimatic 90w (golden colored) oil since... And, it was the second half, or two-thirds even. The only brass piece I know of is around the shift arm at the top of the LU. Could this be corroding?

 

[ob]

Re: blue streaks in drained lower unit oil

My recommendation would be to go ahead and refill with fresh lube ,run it for an outing and redrain , and inspect the contents.If there was no sign of water in the lube you drained initially ,I wouldn't think corrosion would be an issue.Do you remember whether the lube you drained when performing the re-seal job had a similar color?

 

[kenmyfam]

Re: blue streaks in drained lower unit oil

I am with the 2 different weight and colour gear lubes in there theory.

 

[MC Degner]

Re: blue streaks in drained lower unit oil

The lube drained before the reseal was creamy/milky tan. I don't recall there being any blueness to it. That is why I am confused, because I did not put in two different lubes since then, only the aforementioned lubrimatic golden colored oil. There was definitely no water in it this time, just a substantial amount of blue color. At first I thought it could be very finely ground metal filings, but ruled this out as they would not be that blue and also made no response to a magnet.

 

[ob]

Re: blue streaks in drained lower unit oil

A real head scratcher for sure.