[JWCACE]

I had synthetic put in the differential today. My mechanic did the swap but said he noticed some metal in the old fluid (20k miles). Good thing I did the swap.? or ...should I be concerned?

 

[Ironmancan]

Any pics? How big are they. Any noise after install? Not surprising to get some metal but it should be very fine in nature.

 

[dealernut]

That is probably the beginning of the infamous "wine"

 

[QSGTO]

It is normal to get some metal from the fluid when changing it. If any of it is larger than a peice of glitter, the gears are shredding and you should consider upgrading. If you are driving it hard, you should change the fluid every 5K miles. It is expensive, but cheaper than gears.

 

[Subdriver]

It is normal to get some metal from the fluid when changing it. If any of it is larger than a peice of glitter, the gears are shredding and you should consider upgrading. If you are driving it hard, you should change the fluid every 5K miles. It is expensive, but cheaper than gears.

:agree

On the track, I change out my diff and tranny fluid at what equate to about every 500 miles. Probably overkill, but... my tranny and diff get really hot on the track...

 

[johnebgoode]

Drop the fluid again in 1000 mils and take a look. If there is any metallic residue , be prepared to have the Diff changed in the future.
IMO.... there shouldn't be any signs of metal wear in fluid at any time. Considering the notorious whine , previously mentioined, these signs of wear are indicative of a poorly set up ring and pinion. Welcome to the club

 

[QSGTO]

I do diff services at my shop all the time. I have never seen a diff that didn't have metal stuck to the magnet. It is normal wear an tear on any vehicle. It is just worse when you add mega HP.

 

[GopherRick]

*edited, see below*

 

[S2kracka]

(this is GopherRick's son)

Metal particles in diff fluid is normal, especially on the break-in oil. When changing the fluid its always a good idea to do it hot so when draining the fluid carries the particles away while they are suspended before they settle. Also, make sure to wipe of the drain-plug as well as possible. I personally drive an S2000 and the break-in diff oil practically comes out gloppy if its done after 15k miles. When are you GTO people normally changing your factory-fill diff oil and what brand/viscosity are you using?