I had a sheepskin seat on my 78 Honda 750K, it lasted for years, and went through many machine washings, and was always as good as new.
This and a motorcycle to boot!
If yours has not lasted, maybe it is poor quality backing material, or not sheepskin.
I never treated mine with anything, and put it through hell and back.
Maybe an idea for next washing, is to see if you can put it in a fabric bag, with a drawstring, and then wash it, this might be less stressful on the stiching etc...
Best of luck
Baaaaa!
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Chris Ecklund
98 300 DT