Hi guys stupid question but where abouts do u check the level of oil I'm my gear box. I have a slight leak at the rear crank seal side its not leaking from the engine as I've check the oil level and it's not changed. so I guess it's a seal inside the gear box want to check the level to be on the safe side and how much should be in there. also if it has lost oil what oil to put in to top it up so if some one could point me In the right direction it would be very help full thanks in advance nick.