i topped off my steering box a bit ago with some standard castrol 90w gear oil...so far it hasn't leaked noticeably, but if it does i'll replace the seal rather than pack the box with grease...have to agree with papajam that that would be avoiding rather than fixing the problem.I know the topic of "oils" can sometimes go nowhere but, while were at it... what is your current favorite oil for:
as for the rest...
one of the first things i did when i got my car was to replace the transmission and diff oil, since i had no idea when they'd last been done. i used redline 75w90NS in both, and added the redline friction modifier to the diff, since my car was updated at some point with one of the limited slip variety.
since i was replacing used oil with fresh, and i don't know what was in there in the first place, i can't really compare the redline to another brand...however, it did make a significant difference in both cases.
transmission: smoother shifts, and my slightly funky second gear synchro behaves much better.
diff: half cured the reverse judder i was experiencing when backing up an incline (fully cured once i replaced the transmission mount as well).
i'm sure there are other good oils out there, but the redline seems to be working well for me.