I've had my brake fluid changed out at the dealer twice--with two different cars (Mini and 325i)--and both times they took out the basket inside the reservoir and didn't replace it. I'm assuming it's not really necessary to have it in there.....is it?

Gary

 

It keeps trash from falling in when taking off the cap or filling. Trying to fill the res. with the strainer in place you will likely overflow the strainer not necessarily the res. due to the fine mesh. They left it off because they see it as an annoying prank by designers. (saran wrap on toilet bowl)