Considering that Wal-Mart has synthetic for cheap, I wouldn't know why you wouldn't use it.
the $ is no problem i get valvoline synthetic for nothing the reason im asking is that i rebuilt my calipers twice before and used synthetic and each time i end up with a spongy lever, and the reason why its spongy is because when i release the lever the pistons retracted way too far so the next time u pull the lever the pistons have to travel all that extra distance to make up the slop making it spongy i thought maybe the synthetic has something to do with it
when i release the lever u can see the pistons retracted at least a 1/8 of a inch anyone know why????????? im puzzle fucked
and no there is no air trapped in the system i have a bleeder on the master cycl and i bleed this thing every way known to bleed a brake system i probably bleed 50 gals thru this thing
i also know that there is a tapper to where the seals sit in the caliper so its impossible to install the seals wrong