Put a can of upper engine cleaner through it, finally got round to replacing my leaky rocker cover gasket. Managed to get 5 of the bolts out within 10 mins, then came across this:
The 6th bolt was rounded, such a cunt to loosen too as it was right in the bottom right corner. Ended up using a vice. took more than 45 mins to get it off. Now I've got to wait till Monday to get a new bolt from winger(unless someone has a spare one I can buy tonight or tomorrow) then put it back together and chuck some new oil in. What a pain