I went to Oil can Henrys today to have my rear differential service done in my mustang with redline synthetic gear oil and the guy recommended changing the manual tranny fluid as well. I had a brand new clutch put in about a year ago and people told me the only time u need to change the 5 speed tranny fluid is when u have service done or a new clutch put in. But the guy told me this is not true and wanted to charge me 50 dollars to change the fluid even though it was pink and looked good. I did a search and didn;t come up with good results so please forgive. Any input guys?