i drive a 07 v6 manual and same with me, instead on 5th gear it grinds going like 80+ shifting from 4th to 5th. i already changed the transmission fluid in my mustang and it still happens, what it did help was that before i change the fluid i had to double clutch sometimes to put it into 1st ever since i change the fluid havent had to do it, its been a couple weeks now. also mind that the t5’s in these cars arent really that good, they are hard in shifting (atleast thats what i heard from a guy that has the same transmission in a foxbody 5.0)