Here's the general outline of necessary steps to change the oil pan on the 3.0 liter e53. Its mainly a lot of disassembly but as long as you just take it step by step, and you're mechanically inclined to a degree, its do-able. For first timers, make sure you have a back up car in the event you cant finish over a weekend's worth of time.

1. Drain the engine oil.
2. Remove / disconnect the following:
· Bulkhead heater
· Fuel injector Cover
· Mass Air Flow (MAF) sensor and boot
3. Attach an engine lift and hoist to engine.
4. Remove top left and right nuts on engine mounts
5. Raise the engine about 0.15 inch (5mm).
6. Remove and disconnect the following:
· Front splash guard
· Reinforcement plate
· Left and right swivel bearings
· Output shafts
· Propeller shaft at front
· Alternator drive belt from belt pulley for vane pump
· Power steering pump and move aside with the lines still connected
· Return hose from oil separator
· Dipstick tube
· Steering spindle from steering gear tie rods
7. Temporarily reinstall the left and right swivel bearings and connect with a bolt to the spring strut.
8. Support the entire front axle assembly.

NOTE: The steering gear will remain bolted to the front axle support. Return hose must not be over-stretched when front axle is lowered.

1. Detach front axle support from engine carrier and lower about 3-4 inches (90-100mm).
2. Remove the front axle differential.
3. Release the screws on the oil pan.
4. Move the pan backward when removing.