anti clockwise mate,lefty loosey righty tighty, mine was real tight 2. if its that bad get a shifter on 2 it
the germans designed it, the aussies built it, the japs got it moving and the wogs got it dosing...
my cap also jams and needs to be undone with multigrips, maybe this is common?
Yeah it's fairly common, heating and shrinking with hot and cold.
Go to Nissan and ask for an R31 oil cap, there's has a built in torque thingo that doesn't let you tighten it past a certain point. Miles better.
Careful when you use multigrips or a spanner, they get brittle after lots of hot/cold changes. brace it if you can.