Originally Posted by Takamo
Best thing first is to replace the battery, it's the same battery as a Nissan micra cheap as chips, but as a one you can use jump leads off another vehicle to get it started until you replace the battery. Best advice is don't start the other vehicle this way your voltage will remain lower and should be enough to start your car without overboosting the electrics with higher voltage.
So your saying I just connect the battery's in parallel and don't start the first car? Just try to start the GT-R then? I never heard or read about this method