VT S2 5 Speed Gear Box noise

[VTEZN]

Hey guys hope you can help me out with this anoying noise im getting from my gearbox. Its kind of a ticking noise, Kinda like the sound you get when your low on engine oil. I checked the oil it was full, though the texture of the oil was realy black and thin i diped my finger in it and the oil ran off my finger like water. I know that your sposed to change the Gear oil every 40K. So ill be getting this don on tuesday. I just wanted to know your thoughts and to see if you guys have had the problem Its a T5 and the noise is more louder when going down gears and louder on acceleration. Thanx for the help guys

[VTEZN]

can anyone help me??
any ideas?