The 2009 Mercury Grand Marquis LS is a very easy car to maintain. Checking the transmission fluid level is no problem, as the dipstick is easily accessible in the engine bay. Not every model includes this dipstick. Changing the engine air filter is no problem, as you only have to disengage a few fasteners for access to the filter. These fasteners are easy to disengage. The reverse light is easy to replace, as the bulb assembly is easy to access on the inside of the trunk lid.
Some things are more problematic on the 2009 Mercury Grand Marquis LS. Replacing the center brake light can be a problem, as you will have to use tools as you work in a cramped space. To change the parking light, you will have to completely remove the bulb housing. This will require you to remove bolts, which are very hard to reach with reliability. Setting the clock can be tough, as you will have to complete unintuitive steps to change your time.
Hans Angermeier has produced over 100,000 videos showing drivers how to fix things on their cars. He has broad expertise on basic repair procedures covering the majority of cars on the road.