Going to change the Oil/Filter in Pinky, any particular oil to use/ avoid.....Thanks

Does this long read help? Car Bibles : The Engine Oil Bible

If you change it refularly enough (5000 miles) I guess I'd probably not worry too much on the oil. 15w-40 might be the best viscosity, or 20w-50 if any evidence of oil leaks or loss.

felicity seems to get a bit of a turbo charge when i gave her some nice fresh 10w40 semi synthetic to drink. But im a bit fussy about my oil changes and i do them about every 5 months (4ish thousand miles). its quite satisfying to see the oil coming out the same colour as what goes in!

only problem is she now has a drippy oil leak. Which brings me on the the question,

on the 1.3 mpi engine about 6 inches to the left and 3 inches up of the oil filter (as you look at it) there is a random bolt going into the engine block. This is where she is dripping from. This bolt appears to serve no purpose on my car. Ive unscrewed it and cleaned up, also given it a nice new squishy copper washer BUT IT STILL BLOODY DRIPS. If you think its safe to, shall i just undo it a bit and cover it with instant-weld? jobs a goodun then i think!