Black Gearbox Oil

[TwoFish]

Drained my gearbox oil this morning & it came out black. No filings on plug & not milky. Motor has done about 30 hours & 10 mths since last change. This is the first time I have changed the gearbox oil myself not sure what to expect. 1998 75 force. 160 hours total.

Is this normal?

 

[roscoe]

Re: Black Gearbox Oil

It all depends on what brand lube was used.
Some of it starts out dark blue, or black, or golden, or almost clear.

It usually doesn't change color.

 

[redfury]

Re: Black Gearbox Oil

The only reason for the gear lube to change color would be from overheating, or contamination. Transmission fluid in your car only needs to be changed every 30,000 miles ( more or less depending on your car manufacturer ) because the fluid never gets overheated (under normal operations ) to break it down. The red tranny fluid turns brown due to neglect, black due to severe neglect ( don't ask me how I know this )

 

[TwoFish]

Re: Black Gearbox Oil

The oil does appear a dark blue/green color. I have no other reason to think there are any problems with the gearbox other than the color of the oil. I?ll call the shop that serviced it last time to see what color oil they use. I?ll just refill it and check it after a few hours running.

Without the backup of people on this site I wouldn?t have the confidence to work on the outboard. I used to consider the motor to be something on the back of the boat that I hoped would start when I turned the key. I?m now slowly gaining confidence in the motor & my ability to keep it going.

Thanks again for your replies.

 

[jerryjerry05]

Re: Black Gearbox Oil

Just running it for a season it shouldn't be that bad.It sounds like it might not have gotten changed for a long time.
You never know when it was serviced last time if it was really done.
After 30 hours change it.
Keep an eye on it.Check it after the next use to see if it's ok.
I had a pair of 85's and they had good seals(I thought) I changed the oil and went out a couple of time and doing the checks I do I looked at the oil and the starboard motor had water in it.One week ok next week OH NO!!! J

 

[TwoFish]

Re: Black Gearbox Oil

I had changed the oil a couple of months before the last service with quicksilver gear oil (clear in color). Oil that came out was also clear (had about 20 hours use). Serviced at Mercury dealer with a good reputation inside the trade. Looks like they used Mercury High Performance Gear Oil ( Blue/ Green in color). It says on the bottle not to mix the two. Whether this had something to do with the dark colour of the oil? I used the High Performance oil this time.

I will check it after a couple of trips.

I take it that I should use new washers each time?

 

[jerryjerry05]

Re: Black Gearbox Oil

I do.It's under $2 Good insurance.J