My 2014 Tbird LT has less than 6000 miles but has developed a problem with clutch slipping under hard acceleration. The clutch lever had to be almost totally released before I was getting engagement so I adjusted the lever and cable so it operates more normally now but I'm still getting the slipping problem. I'm using Castrol 10W40 Actevo X-tra 4T Oil. Any suggestions on other adjustments I can make, different oil, or am I going to need a clutch disc replacement? Thanks!