argiad 
2005 Nissan Xterra SUV S Rwd 4dr SUV (4.0L 6cyl 5A)
Faulty radiator design destroys transmission
 I too loved my Xterra up until a couple of months ago.Bad engine design results in a faulty radiator part leaking radiator fluid into the transmission, destroying the transmission and leading to upwards of $5-6k in repair costs.Early signs include a low rumbling while driving as though driving over rumble strips and disappear if you slow or accelerate.Do NOT ignore this!If you do you could end up with engine overheating at best or transmission failure while driving possibly resulting in an accident.This problem occured for me at 90K miles is a common occurance and for others has occured at as low as 50K.Nissan is fully aware of and has done nothing to fix the problem.