I've got a small oil leak coming from between the bell housing and the gear box ?

What could it be ?

Blacktop + tran x gearbox

If it's engine oil, then most likely is crankshaft rear oil seal.

If it's gear oil, then spigot shaft oil seal.

gearbox oil smells like bad eggs just in case you cant tell the difference

check the gearbox and gearbox breathers are not blocked before replacing seals, sometimes gearboxes are painted and the breather is simply a very small hole which gets plugged with paint causing the air pressure inside to get too high for the seals when it warms up

Had a look and it's engine oil. There's not really that much. Just a thin layer.
If its this crank shaft seal. Should I worry. How do u change it?

[Edited on 31/7/12 by andy996tt]

I wouldn't worry if it's only slight, the worst bit is the mess it makes so if you can live/cope with that I'd leave it.
If it's engine oil which will almost certainly becoming from the rear crank seal behind the flywheel it gets flung outwards by the back of the flywheel & coats the inside of the bellhousing & then slowly drains to the bottom where you see the leak. This means it rarely gets on the clutch where it could cause a problem.
If it were gearbox oil then it'd be of more concern as it would be far more likely to get on the clutch & as the gearbox holds less oil & is less easy to check & top up you could end up without enough in the box.
Fixing either would mean seperating the engine & box meaning removing one or the other from the car, if you can live with it then you may want to have the engine or box out for some other reason at a later date & fix it then?

As said, check the breathers as many folk have chased oil leaks that would've been minimal if the breather had been OK!

Cheers for the reply.
Will leave for now and keep it in
Mind if I have any engine out work done