I just swapped the gearbox and r/diff oil in my Alfa Spider (with Redline GL5 70W90 and ns (gb)). The drain plug of the diff was covered with about a quarter inch of pasty gray goo (really nasty stuff). The gearbox drain had a film of it, too, though not as bad as the diff. Can I presume that the shop hasn't been changing the gearbox/diff oils? (The Alfa only gets about 1500 mi/year.) Do I need to change oil again in 500-1000 miles to "flush" the box? The drivetrain is much quieter with the Redline in it. BTW: I have little sense of smell, but even I found the gear oil stench overpowering. Should I have been in MOP3 gear to deal with this crud?