I've had my 05 Frontier V6 CC since Dec of 04 and the only mechanical issue I have had was the intake rattle at a certain RPM but was taken care of a LONG time ago. My truck is 100% stock with 56k miles and has gone through regular maintenance through Nissan. Lately I have been noticing what seems to be the cooling fans on at all times (maybe not sure) but for sure no matter the temp, even cold, when I take off I can hear the fans very audible over the motor itself as if the fans are spinning up really high with the RPM revs. Kinda reminds me of an 18 wheeler taking off the way it sounds with their huge fans. I did notice one day last week when I was idleing with the a/c on full blast on a hot day the temp needle went to H for a second or two then went back down to normal soon after. I've been monitoring it now on a regular basis and have not seen it go back up since even when idleing. But the fans are definitely humming along very loudly as the motor revs that's for sure.