My leaking rear diff
 

So my rear diff has been leaking for about 6,000 miles and finally had a chance to get a opinion on what it might be. I emailed some pics to my friends shop and was told I would need both axle seals and rear plate seal $550 with bmw fluid and bmw gaskets and a few hours of labor to complete

How's that price sound? This price is coming from someone I trust 100%

1

A few questions, why only since 6000 miles? If you've (recently) checked the oil level and that it's about right - perhaps you're not loosing that much. Did you (already) entirely clean the exterior housing (kerosene is a good solvent) and then monitor to determine if it's more the rear housing gasket (easier and cheaper to replace) rather than the input or one or both of the flange output seals?

I'd definitely clean it off and confirm whats leaking first.

There's nothing wrong with replacing both axle seals while its in the shop....but the passenger side looks high and dry, so it I wouldn't really say it's warranted. The drivers side is definitely toast though.

When i purchased the car the seller washed down the car from top to bottom so the PPI mechanic couldn't find any leaks. I never really notice any oil spots on the floor but I would pressure wash the diff or use brake cleaner and after a while I would see it back covered in oil

Yea I figured why change just one side

Do u think the price is fair?

In all honesty, I'm about the last guy to talk to about how much a repair would/should cost. Im fortunate to have a buddy whose dad grew up with my dad and owns a transmission shop (giving me access to all kinds of luxuries for working on the X)...and lucky enough to be able to do the jobs you simply can't do at home easily, after hours or on weekends at the shop on my own time.

Is this a DIY job or something a shop should handle

Can't help you on how much it should cost-differs by location. Best way is to get a second opinion.

Can't tell if the cover gasket is leaking or the leak from the seal is running down and making it appear to be leaking. I would confirm the cover gasket is leaking. If it is only that one seal I would consider not bothering with the gasket or the other seal. It the cover gasket is leaking then doing it all makes sense.

DIY of Differential cover and output shaft seals is a heavy job but not all that difficult. You will need a puller tool to remove the seals. You may be able to rent what you need from a local autoparts store.

To replace the cover seal the differential has to be removed. It is heavy so you will need to support it with something. The seals can be replaced without pulling the differential. If you need to do both cover seal and shaft seals it would be easier to do the seals after Differential is removed.