Good morning,
This weekend I set about to rotate the tires on the XTerra as it was pulling to the right and I was unsure when the tires were last rotated as I just recently acquired the vehicle. I wanted to swap them left to right just to see if she would pull to the left or track straight.
I also popped off one of the drums just to check on the rear brake wear while things where disassembled...that all appeared in order.
Anyway, after putting everything back together...the truck doesn't pull to the right anymore, she now pulls ever so slightly to the left. My whole theory is that something either has to be wrong with the steering linkage or you have to hit something pretty hard to whack the alignment out.
So I would suggest that you all rotate your tires, every other oil change should be sufficient, that's what I do on the other vehicles.
Bogatyr