I added some brake fluid recently (for those of you who dont remember) and i'm getting grinding noises .. not very loud .. 30% of the time i start my car. it lasts for about a second, but its a sound that concerns me..

 

This also has nothing to do with the brake fluid.

When the grease in the starter starts to dry up, it doesn't disengage as rapidly as it should when the car starts, so you get that awful sound. Go to http://www.motorvate.ca look under the engine section and click on starter noise fix. This is probably your issue.