I have a VS V6 manual (getrag) and am annoyed with the amount of diff clatter (play) with the Castrol SAF-XA synthetic diff oil in it now. The SAF-XA is suppose to be rated at 140W when hot but you wouldn't think so with the amount of play between the diff gears. My questions are: should I change to a thick (140W) mineral diff oil to reduce the play, and if so any particular brand?Will I lose power by changing to a thick mineral oil in the diff? I rather put up with the play if I will be losing power changing to a mineral oil. PS The diff is NOT LSD.

HHHHHHHHMMMMMMMM........... OK then. How about you just run the standard ****..... 80W90. 8O

The diffs only 54kms old ('97). Basically I just want to know whether I should leave the synthetic oil in there or change to a thicker mineral diff oil-90W or 140W?