Changing spark plugs and wires on 1989 300 e . Also is changing oil very hard

Changing the ignition leads is a fun game and takes patients as they are routed inside a plastic casing. (normally missing) The casing splits in two, remove and replace the leads one at a time ensuring they lay flat whithin the lower part of the casing this will make fitting the top part of the casing easier. As for the oil change, it is best to run the engine before hand maybe with a flushing additive in the old oil, once warm (normal engine running temp) TURN THE ENGINE OFF, undo the 13mm sump plug and drain into a suitable container - leave the sump plug out and remove the oil filter found to the left hand side of the engine - a black round plastic cover approx size 5" diametre- note the tightening torque stamped into the cover. Replace filter and seal and refit housing. DONT FORGET to now refit the sump plug, the reason for leaving it out up to this point is to allow as much of the sludgy deposits to be drained away. Now refil with the appropriate oil. Job done.