Black gearbox oil

[The Black Pig]

Just changed the oil in a tohatsu 60c it hasn't been done since it was new about six years ago it was jet black but without any smell I could detect,

Maybe it is what I should expect?

[cptsideways]

Some new oil was jet black a few years ago

[Locozodiac]

For opt lower leg conservation you should change gear box oil each metered 100 working hours. Can use any good quality gear oil grade 90 or multigrade 80-90. Drain well old oil before new one is filled in.

Happy Boating

[henryfreston]

Black is fine, it is when it is creamy colour you have to worry (seals have gone/perished).

[kubcat]

It is possible that the oil you have over there is different and started life as black but if my gear oil was black I would think it has overheated at some stage and is not lubricating as well as it should. The problem we have with offshore boats is that running engines higher than normal with more of the gearcase out of the water limits seawater available for cooling, causing the oil to go black and the gearboxes blow up shortly after as the oil is no longer lubricating, but the oil normally smells burnt. Maybe only a problem with modified high performance motors, maybe not. Just my 2 cent worth.

[yam man]

Originally Posted by The Black Pig

Just changed the oil in a tohatsu 60c it hasn't been done since it was new about six years ago it was jet black but without any smell I could detect,

Maybe it is what I should expect?

So never change even a on 20hr 1st service .

[Bigmuz7]

Marine gearbox oils have other additives in them , so I'm not sure about the colour. Most ordinary EP80/90 oils Ive used (including marine ones) are clear yellow ( if you follow me) and when most start to break down they will turn black, but also smell strongly like natural gas, in doing so.

When they get this way, they dont offer the correct lubricity and should be changed promptly. And as already mentioned, milky colours are water contamination

On land based products using gear oils, Ive noticed the speed of break down is relative to a number of factors, namely, the oil capacity of the box, the amount of gear surface area using the oil, and the loads placed upon them. I've not had any outboards that have been particularly harsh on ther gear oil, so I imagine they are loaded moderately or well enough designed to have the right amount of oil servicing that particular gear area.

That said .. Ive always done them every couple of years, so as to inspect for possible water ingress, and my use is only light leasure

[Locozodiac]

Tohatsu's original gear oil is yellowish when new, if used for extended boating periods usually comes very dark, not good if oil has severe metal fillings contaminants, expect light to none filling contamination on first oil change, but that's normal, gears are molding nicely in between them.

On Tohatsu new engines you must change first oil at 10-20 worked hours, don't know if the gear box comes factory full or with less quantity as manufacturer assumes you will be changing it shortly. Yesterday changed a 18 HP enginhe first oil at 60 metered worked hours and came inmaculate clean, a pity to drain and change...

Happy Boating