M54? Tstst is 3/10 difficult one of the easier jobs. Just follow the steps ding try to take a shortcut like leaving fan shroud on (personal experience).
A neat trick i do to reattach the fan is to wrap electrical tape around the nut about six wraps (clockwise while looking at the nut opening) and keep the roll attached as a handle. Pull slowly to turn the nut.
I broke my thermostat by using the hammer on wrench method to loosen the fan while the coolant was under vacuum making the upper hose stiff! So learn from my mistake.
Sender for oil looks like this. Had to change the gasket on mine recently was leaving several oz of oil every day on the ground.