Have just bought a white C180 manual ( 1999) which badly needs oil change. This is my first MERC and I am over the moon ! I have a special tool to remove oil filter housing but am wary as I have no knowledge . I have a filter and what looks like very large circular rubber seal. What spanner size ( or plug wrench) do I need to loosen sump filler plug and what pitfalls do I have to watch out for? All advice gratefully accepted