hello, i have a 940 1997 i bought it in 2011
i took it into a garage today for an unrelated issue and was told i had a problem with my diff . oil low teeth grinding. i havent noticed any noise at all. or problems, he said it was leaking but i think the leak was fixed before i got the car because the oil stain looks old
adding a photo,
what do you think
do i or dont i do they leak when topped up

 

Is the oil now low or not? The leak "looking old" is not a good diagnosis. Seepage like that, as minor as it is, over the years will deplete the diff fluid--it doesn't hold so much to start with... At any rate you may want to just keep it topped off even with a leak like that, it leaks slowly, it will hold for awhile...

 

Just check the fluid level and top off if needed. Keep an eye on where you park for stains and check the rear...most likely it is a slow leak BUT that oil also services the rear axle bearings at the outboard ends of the axles. Important that fluid levels be monitored.