in a real car the locked diff will cause plenty of oversteer and push understeer depending on throttle application. It is a cheap, but nasty way of achieving better transmission of power from engine to ground. The same must be true for a 1/5 scale, with less negative impact on other driveline components but there will be some. In essence you are creating a spool diff, very viscous oil, perhaps powdered grease or playdough packet very tightly.
I have used blu-tac in 1/10 cars but they don't have the torque thus it works.
Justin
