Previous threads have mentioned semi synthetic oil and probable cause for clutch slip. My A4 was running on Castrol GTX with no probs; did an oil change 300 miles ago again using GTX, but this time she started slipping at between 4-5k. So at the weekend did yet another oil change: I used Castrol ACT EVO 10-40 Mineral: states on the marketing bumph "for use in Classic Bikes" - gobsmacked, but it actually fixed it: 100+ miles and no hint of clutch slip.
Not sure if anyone else had used it - but seems to have cured (one of) my A4's gremlins.
Cheers Tim
"Better to remain silent and be thought an idiot, than to open your mouth and remove any doubt" - Abraham Lincoln
Z900A4 / Hodna CBXZ / Ducati Diavel / H1F 500 Mongrel / CBXZ Project / RD400 project