Edit: Yeah... as mike says...
Hi Matt,
the large bolt in the photo is the oil drain plug (sump plug). If you are sure the oil leak is coming from this bolt, and not from somewhere higher up, i would suggest fitting a new copper sump plug washer. This should be done on every oil service really - have you had it serviced recently? I would not sugest tightening the bolt as the threads can easily be stripped in the sump.
Procedure:
You will need,
24mm socket & bar, torqure wrench for doing it up afterwards
5L of 20W50 oil (MUST BE MINERAL - not semi synthetic - do a search for good oil, but people generally say millers/halfords classic/duckhams / unipart)
New sump plug washer - pence
New oil filter £2-5
Remove bolt.
allow oil to drain
remove copper washer from bolt, fit new one, screw in bolt. Tighted to 25Nm, does not need to be tight.
Remove old oil filter
Fill new filter with new oil, smear a little oil on the rubber seal.
Refit filter.
Refill oil to max on dipstick.
Run engine a few mins to circulate oil, recheck level and top up.
Should take 30mins or less.
Ryan.
Edited by L400RAS, 02 July 2009 - 06:26 AM.