R380 Gearbox Oil

[130CC]

Ok so this is not the normal post like what type of oil does it need, use or what different brands fix certain things reduce noise etc.
It's more like how much is it going to cost this time, type of question.
Around 15 or so thousand k's ago I replaced the gearbox oil. The strange thing that I found was that there apeared to be sliver paint through the old oil. Bugger something is f#*ked, I was shocked as I had no problems shifting or any noise more than normal. So when putting in the new oil I thaught to myself well I will wait and see what happens in 5 or so more thousand when I will change the oil to see if the problem is still there. I only did this because there was no sign of difficuilty shifting or noise or anything else. So on the next change the oil was perfect not a thing looked as good as new. Needless to say 10 or so thousand k's have gone on the dial and a small amount of dificuilty has started to happen when shifting bugger I had a feeling that this was going to happen. Once again buying new oil I drain the box to have a look at there was this silver paint (metal) in the oil. I no longer feel that it would be wise to continue my current plan of attack. The box has to come out (this is just an asumption) and a replacement go in or fix the old one or is it not that serious( still trying to be an optomist). All I am wondering is what could be causing the problem? Also just in case someone might ask there was next to no fur or larger pieces of metal on the gearbox drain plug all three times.
If anyone can help or has any ideas.
Thanks Adam

[130CC]

Update
Part of the problem was worn syncros the other is related to heat the gear box has gotten hot and has caused problems. All gears were in tact but the bearings, syncro's and other bits that hurt the bank had to be replaced.
Just a warning to other people who were talking about warm transmition tunnels and the like it might pay to have it looked at.
Adam