Clutch

[Slamtry]

My clutch broke this last weekend. This is on an un-modified '91 Classic
with about 155,000 miles but which had already had a clutch put in when I
bought the car at 95,000 miles. The guy at the shop who just installed the
new clutch said the "clutch spring" broke. I have a couple of questions to
anyone knowledgeable about clutches:

1)Isn't that very low mileage for a clutch to break? I don't thrash the
car or drag it or anything. Could it be connected with my having put in
Redline MT90 about a month before? The reason I want to know is because...

2) The mechanic also just told me that he did not save and re-use the
MT90. Instead he put in ordinary 20/50 engine oil. I mentioned to him that
the manual says to use GL4 manual transmission fluid, but he said that the
engine oil would work just fine. Now, he is a pretty good mechanic and I
tend to trust him. Is he way off base here? Do I need to change it? And if
so, can I use Redline again or might that have contributed to the early
failure?

Thanks for any help here.

Dan Hugh-Jones