Metal flakes in transmission 90 300D
 

My 1990 300D transmission has not been shifting into 4th gear for a while. The problem has become worse as the temps have fallen. I decided to change the filter and fluid to Mobil 1, since I have had good luck with it in my 85 300SD. I drained both drains, and removed the filter. I noticed that there were metal flakes/chips on top of the filter, and none in the pan bottom.

The car will also roll back on a steep hill while in drive, doing so very jerky. It seems to shift fine once warmed up. The car has 280kmi on it, and has seen regular tranny service.

Is this something that I should worry about? I am not sure about dumping that expensive oil in it now, only to have it fail in a little while. Should I use just plain ATF? Should I even try to drive this car with this tranny?

Any help is appreciated. Thank you.

Also, I forgot to mention that the flakes look to be at most .75mm, and are all square in shape.

thanks.