Differential fluid change, 2003 GM

My 2003 Grand Marquis has 97,000 miles. When I took it to my ford dealer for an oil change, they said the differential fluid was dirty and should be changed, $120. I've never changed the differential fluid in any car I've had.

Is this a legitimate need, or is my dealership trying to make work for themselves?

I do want to keep the car for another 100,000 miles.

I don't have the owners manual in front of me but I think on my 1998 it said no change needed for the life of the car. I'll look in my 06 manual when the wife gets home. If you want another 100,000 out of it I would probably change it. Check your local quickie oil change place instead of the dealer. Jiffy lube gets $37

The only way to drain it out is to remove the differential cover which is sealed with RTV from the factory. After having to do two bearings and rear axles on our 2003, I'd definately reccomend changing the fluid to maximize the life of your rear wheel bearings and axles. I don't think 120 is unreasonable for that job. The tech needs to scrape the old RTV off the cover, and properly apply new sealant. It can be a time consuming job.

There isn't a fluid in the vehicle that should be changed on or before 100,000. Even synethics(sp) need changing. I took mine (a 99) to the local valvoline quick change around the corner and paid about $50. I got there and watched the guy do the work and talk to him so he'd not screw up the work.

Also, make sure they add troq loc if you use a local quick change shop. Mine needed 4 oz.'s of troc loc.
It ensures the limited slip differential locks in. Actually limits the "slipperyness" for a lack of a better way to say to allow the limited slip to kick in.
Like PC sez above you'll have to remove the cover off, scrap both surfaces of all RVT material to make sure you can seal it properly. You have to be careful you do not nick the surfaces - it can compromise the seal

I dislike working with trans & differential fluids - it's nasty.
There are times when I let the check do the work for me...

I actually assumed our 2003 had a traction lock LSD but I was surprised to find out after doing a lot of research that very few Grand Marquis actually have a locking differential.

PC - there's an old movie out about the first New York state lottery winner with a reference to Bud Lake New Jersey. First off it's great movie and my oldest daughter was born in New Jersey (couldn't get back to Michigan in time) and my uncle there for the phone company. I like the west end of the state for fishing...

Haha well it's a decent place to live, I grew up in Budd Lake. I fell in love with the southwest when I studied engineering at Arizona State University in Phoenix, but the job market out west is pretty rough right now. I'm interviewing for jobs in New Jersey so I can minimize expenses for a while by living at home, but as soon as I see the job market picking up out west I'm going back to the warmth. Cold snowy winters just aren't my cup of tea. I'd probably appreciate NJ a bit more if I hadn't spent most of my life here.