So my third gear recently started making a scruching noise in my evo 7 (5 speed). It doesnt do it with any other gear only third, But when i drive the car for 10miles or more the scrunching stops, what would be causing it to just scrunch at the start, is it something to to with the synchro for 3rd gear?

 

What fluid is in the trans? Also how long ago (mileage) was it changed. Most people will recommend diaqueen bjt there is two or three other trans fluid that are popular. If fluid is fresh OEM, id say chances are it is worn syncros. Wouldnt rule out checking all linkage tho just to be safe.