Gearbox oil level

Hi all,

Changed the transfer box oil today - had it up on a ramp so very easy access. No probs. Quite delightful in fact to do it up in the air in a nice warm garage, instead of lying on my back in grit with ATF pouring down my sleeve and into my face.

When I went to change the gearbox oil, I stopped after about half a litre had gone because it'd obviously been changed during the torque convertor repair (Duckworths) only a few hundred miles ago. But when I dipped it to check the level (having run it, moved it through the gears etc), it was actually quite a bit above the max, even with half a litre less than was originally there. I didn't bother draining any more as by that time I'd tidied everything up.

What's the result of having too much gearbox oil?

Thanks, David