[Mark e90]

After reading a thread about a e90 that had a diff gone bad I'm a little concerned about mine.

My car has a slight grinding noise from the rear at around 30-40mph, its very quiet and barley noticeable can't hear it when radio is on and i struggle to point it out to some people as you need to be really quiet and at just the right speed to hear it so thats the kind of volume it is.

The noise has been there since i bought the car and over the course of a year and a half and around 10k miles it has remained exactly the same and has never gone away nor got any louder. At first i thought it was the rotors grinding on the heat shields as that exactly what it sounds like. I did investigate all the brakes / heat shields and after around the 10th time i gave up on that being the problem as i am 99% sure its not that as everything seems to be in order in that department.

It did really annoy me when i first got the car and was determined to solve it but its so minor that after a while it was easy to just ignore and when i got my mechanic friend to have a look / listen his advise was to leave it until it becomes more obvious but the trouble is over a year on its still exactly the same.

I was never really that concerned that it could be the diff as i always just assumed that bad diffs make a humming noise similar to a bad wheel bearing ? Plus i had never heard of an e90 with a failing diff unlike land rovers etc where it can be quite a common complaint.

Im planning to service the diff and see what the condition of the oil is like.

What do use reckon ?

The beauty of browsing car forums, constantly finding new things for me to worry about

[DriverLDN]

I had my diff oil changed recently. I was not suffering any issues with it, I just had it done around 75k miles for piece of mind. I did notice that once it was done, the car did feel smoother and coasted with a lot less resistance. I'd say its worthing doing as its not a pricey job to get done.