I changed the oil and filter the other day. The manual (as supplied from here) says to remove the camshaft end cover, then drain oil etc etc etc. Later it says refit the cam cover. You dont seem to need to do anything else apart remove and refit. My question is why?

The only reason I can think of is to relieve a vacuum that might build up at the top end that would prevent oil draining properly.

In the end I undid the bolts but couldnt get the cover off and as I couldnt find my rubber mallet to whack it with I decided to just put the bolts back in and worry about it next time (perhaps the vacuum was holding the cover on as it was stuck tight).