I recently purchased an 08 manual transmission Mazda3. I have issues where, if the car sits for a while (or if I drive for a while in 5th on the highway), the shift stick gets really stiff. I can wiggle in and it will break free and shift more smoothly for a short time then it stiffens up again. Are these dirty/gunked up shift cables causing the problem? Or could something else cause this issue? I've seen some YouTube videos where they take out the shifter cables and clean them, seems to fix the issue for them, if I've diagnosed it correctly. Thoughts?

 

Try changing the gearbox oil.