hi I recently bought a 2007 Mazda 3 sedan auto from a dealer and iv noticed that when I accelerate the transmission sounds like it's grinding on the gears in the lower gears and has a loss of power till I finally changes(this is between 1st and 2nd gear and loss of power is about half a second), I checked the fluid for the transmission it's a tiny bit discolored, but I'm unsure if there's something wrong with the transmission that will require it to go into the mechanic or a simple fix