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.

What do you consider "a lot" though? Are we talking a spooonful, a pinch?
The rear w/ LSD will shed a fair bit of material as the clutch pack wears. The front shouldn't have much. Either way, if what you're seeing isn't actually unusual compared to others, I wouldn't worry about it, it's not like the Nissan diffs have a history of crapping out.

Brent

I found part of a ring gear tooth on mine the last time I changed the fluid. What's a lot to you?

The first couple changes will have metal shavings as the parts are still breaking in, but you should get less of that as it ages. If the amount of metal incereases or you have large pieces I would be concerned, but if it's just "fuzz" that's normal. Assuming you are correct that the previous owner changed the fluids, it's possible they did it very early on before things were really done being broken in and then didn't change them again after that.

A lot is definitly a subjective term. I always expect a light film of metal on the magnet. It is when it is one eight to three sixteenths of an inch thick that I get concerned. This metal amount is not normal in reference to other transmissions and differentials that I have used and maintained. Clarks, New Process, Eatons, as well domestics in cars and trucks. As for the wear in period, there is a huge difference between seating gears and continually cutting the hard facing. As for the comment about how bullet proof these units are, you need to have a differential with the the hard facing on the magnet and a whine at 45 as a result. Hopefully I don't sound too harsh, but it seems that the A team was sick when my gears were made.

Mine usually have about 1/8 in. on them. I always smear what I wipe off between my fingers to feel for any large pieces which is the only thing that worries me. The largest I've ever had was a piece the size of a grain of sand. The rest is so small it's a thin paste.