2011 malibu 2.4 liter 6 speed auto flex fuel. Thoughts on flushing transmission fluid. I wanna change the fluid since I don't know when it was last. Car fax doesn't have information from previous owner if it was ever done. 119,000 miles almost. I've heard bad stories about flushing the fluid and having issues after it. Would draining out what you can get out be better and filling it?