Every maintream mechanic shop has to go by book hours to qoute jobs otherwise they will not make enough money to stay open. The amount of time it takes to complete a job is actually told by the car maker itself. They list how many booked hours it will take to complete any job and they also give a warranty hourly rate. Like it says 4.5 hours for a non warranty repair but maybe only 2.5 hours if under warranty. This is just how the business goes.
The problem with the oil pan is that you can not just unbolt the pan and have it drop straight out the bottom. There is not enough wiggle room to have it drop down and be able to fish the pan around the pick up tube and baffles in the pan. This is why the repair requires a labor time of 4.5 hours. You have to drop the subframe down several inches while supporting/lifting the engine to make room and slide the pan out.
Will it take most mechanics 4-5 hours to do the repair, no but that is how it goes. There is a labor time for everything you have to do and it adds up to 4.5 hours. Like supporting/lifting the engine is 1.0 hours, lowering the subframe is 1.0 hours, R&R of the pan is 1.0, drain/fill the oil 1.0. It's kinda of like that, it's a bunch of little tasks that add up to the total.
