Can I use "Automatic Transmission Stop Leak" to fix my manual gear box leak?

[MysticMartin]

My wife's car has developed a leak from the transmission. It's bad enough to need fixing but not sever i.e. over a week the level in the box dropped about 10mm.
I found an additive which is supposed to stop such leaks but it's for automatics not manuals.
Does anyone know if I can add it to the manual gearbox oil?

Here's a link: "Wynn's Automatic Transmission & Power Steering Stop Leak"
http://www.halfords.com/webapp/wcs/s...egoryId_255219

Thanks
Martin

[MysticMartin]

I have since found 'stop leak' additives for manual transmissions on ebay. Does anyone know if they are any good or likely to make things worse?

http://www.ebay.co.uk/itm/1706259536...9#ht_878wt_806
http://www.ebay.co.uk/itm/2906669118...#ht_1468wt_682
http://www.ebay.co.uk/itm/2609152677...ht_2494wt_1152
http://www.ebay.co.uk/itm/3006237822...#ht_3228wt_754

Thanks
Martin