Why do the gear related drain plugs accumulate so much metal in my Xterra? I have been in cars/trucks for awhile and have not seen this much metal on drain plugs before. I recently changed all the fluids in my Xterra, and found more than a usual amount of metal in all but the engine and transfercase. This is a used 5 speed unit that I bought with 62K. The fluid that I changed out looked like good synthetic, so my suspicion leans toward a good maintenance program by the prior owner. I saw a post where this is normal for Xterra's, but that does not make sense. That metal has to come from somewhere and the only places I can think of are the hard facing on the gears(most likely), the bearings or the thrust washers. In any case that amount loose metal can't be a good thing for the long haul of a vehicle.