How much metal is normal in gear oil?

I have been searching and searching on google and naxja. how much metal is normal in a diff when you change the gear oil with sort of new gears?

I had new gears installed last year around march, threw a new carrier, new lockright, new hardened cross pin, master install.

I have changed the gear oil like 5 times since then, put less than 4000 miles on the thing in the last year.

silvery gear oil is pretty normal. I get small silverly gear oil plus metal flakes every time I change it? they arent huge metal flakes though. Any ideas? I just wheeled it all weekend and put on a few hundred miles so ill change the gear oil again tonight and post pics.

I would say some are normal. Especially after all new components. I recommend putting a strong, small magnet on the inside of the cover near the bottom to catch everything. Tht will give you a good idea of how much is new vs what's residual from initial break in

A little metal is normal after a new install. It shouldn't still be making metal at 4K miles. If there's so much metal in the oil that it's turning "silvery" I'd guess there's something wrong in there. Is it making any noise?(Can you hear it over tire noise? ) Is there any play in the yoke/pinion or excessive gear lash?


Another magnet trick is to stick a magnet on the outside of the dif cover. When you pull the cover, any shavings are stuck to the inside of the dif cover and can be easily wiped off

Magnet on the outside of the diff cover has no effect.
I've tried it when considering how to add magnets.

I got worried about the front diffs in my Jeeps after having had carrier bearings in the 2nd one fail at 55k (1st one failed at 34k)

Put an ARB front diff cover on both vehicles. TWO magnets.
One on the end of the filler dipstick. the other on the drain plug.

Silvery oil probably should be expected during breakin of new parts.
So frequent changes should be done early.
But continuing metal isn't really normal.

Some "mud" of finely ground metal is typical at 25k mile changes without magnets to collect it. Mud on the magnet should be expected on a GM diff cover. I don't know why Dana doesn't put magnets in.

blondejoncherokee said:

I have been searching and searching on google and naxja. how much metal is normal in a diff when you change the gear oil with sort of new gears?

I had new gears installed last year around march, threw a new carrier, new lockright, new hardened cross pin, master install.

I have changed the gear oil like 5 times since then, put less than 4000 miles on the thing in the last year.

silvery gear oil is pretty normal. I get small silverly gear oil plus metal flakes every time I change it? they arent huge metal flakes though. Any ideas? I just wheeled it all weekend and put on a few hundred miles so ill change the gear oil again tonight and post pics.

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When you first run a gearset, you're lapping the gears together under stress and "setting" the heat-treat (which is why it's so important that you don't overheat the gearset.)

Past about 2,000 miles, I've noted that the normal amount of metal would be "trace to none" - as in, drain it over a coffee filter to catch any metal, pass a magnet over it, and you don't find but a few shavings.

What's your contact pattern look like?

Wow, I think I have a million miles on the road in 40 years now, and only once changed the diffy oil, and that was on D44 rear with 265,000 miles that I thought was making noise (turned out it was drive shaft U-joints). It only had a few pounds of metal in the gear oil, LOL.

i was pretty careful to break in the gears. I think it could be the intstall. Ill have to pull it apart soon. Ill do a drain and fill soon and see what comes through a coffee filter, but I am sure I am on borrowed time at this point. sucks because the gears and master install are brand new as of about this month last year, carrrier too, locker, etc. I dont notice any weird noises, but that doesnt mean much.