I agree with Steve, i have always used coppaslip on clutches and never had a problem on any car
And as for warranty problems because of it? Never had one turned down because of that
You only use a very small amount so i can't see it getting on the lining either. Older Ford clutches used to squeal like a pig if it it wasn't used.
How many of them were a Triumph 1300 which ha a very different input shaft arrangement to any other front wheel drive car?
There is an weak spot on the 1300 shafts due to their design
The Saab 99/900 has an almost identical setup, with the early 99s using the Dolomite engine, I suspect the transfer gears came from the same pen! THEY don't break clutch spigot shafts for a hobby. Even with a Turbo in front of them!
Back in the day I DID fit a number of clutches to 1300FWDs (and probably a handful of shafts) including my mums car I mentioned above. All went in with a smear of copaslip to help them on their way and none came back broken. I never EVER fitted a 2nd shaft to the same car.
I don't claim to be a world expert on the FWD cars, but 50 years of experience, starting with a 4 year MVT apprenticeship on Triumph in the early 70s, has included a good few, along with everything else from Lada to Rolls Royce.
And I repeat, as Matt has, the grease, wrong grease, or lack of grease on the shaft will NOT cause a NEW shaft to fail in less than a fortnight! There MUST be something else amiss!