I've been looking for the oil top up on my gear box and can't find it is it drivers or passengers side ive also noticed it says Borg Warner on the passenger side

 

Also what oil do I use and how much do I put in

 

Drivers side, the plug is just a plug with a 3/8" square hole in the middle of it, so just put a 3/8 drive ratchet in and turn, normal right hand thread.
It takes 2.55L of the closest oil to the original that you can get which is Castrol TQ-D, about Ł9/L from halfords etc, but if it's got lots of wear they are often better with gear oil, but this will shorten the life of the synchros, so only use it if you need to.
tabetha

 

How would I know if it needs the other matey

 

If the gearbox feels ok in use, ie not fighting you in every gear change, or not wanting to go in the next gear esp when changing down, if having to deliberately do a slow change so as not to catch the box out gear change wise, it would be likely down to the synchros.
The use of gear oil in this case can help, it is no where near as slippery as atf(TQ-D) and so helps the synchros by slowing the gears down inside the box due to more friction, the synchros in every box actually use friction to do their job!!
tabetha