Black gearbox oil

[FrEsH]

So since ive had the car, about 2 years, i've changed teh gearboxo il about 3 times..and everytime its as black as night....I find this very odd as it goes in a nice gold and i dont think theres any combustion or dirt in my gearbox Just wodnering are tehre any seals around there that could be leaking crud into it or any suggestions really...its a GT starlet
thanks

[Grrrrrrr!]

Some possibilities:

clutch type LSD friction material
Oil breaking down due to shear/heat (which is why ya change it )

[FrEsH]

hmmm na no LSd in it maybe the second one...elabroate? i changei t really regualrly..like 3 times in 2 years seems pretty good for gearbox oil...

[Grrrrrrr!]

I cant find a decent reference at the moment, but basically as the oil gets squished between the teeth on the gears it can literally get broken up. So your long hydrocarbon chain becomes two shorter hydrocarbon chains. As there is only a very small amount of oil between two gear teeth at any point this is a gradual thing. It doesnt take much crap in the oil to change the colour of it, it could look quite dark and still be okay.

I'd be more worried about bits of metal in the oil which indicates wear of gears or synchros.

[Bumpy]

I was once told, if your oil isn't dirty, it's not working properly.

Could it be the oil you are using?

[FrEsH]

i'm not sure if that holds true for gearbox oil...maybe?

Na used different oil all 3 times

[panda_dan]

Put in some redline heavy duty gear oil. Its pretty expensive at $26 for 900ml at BNT but you wont regret it. And it will solve any niggles in your gearing. Very good oil