lubricant for assembling calipers and MCs

[Konstantin Bogach]

Hi.

Can someone tell me what lubricant I can use for assembling brake
caliper?  I thought I can use brake fluid for this but I found out that
there is special lub for this.  Do I need to buy it? Can I use some
other more common lubricant?

I still can not find information for what ID size of o-ring I should use
if a shaft size is 10mm (ID 10mm turned out to be too loose, in my
opinion)

Thanks.

Konstantin Bogach.