I just bought a 1989 subaru wagon gl. I went to change the brake pads and i cannot push down the caliper piston i was using a c clamp. Does it require a special tool if so what do i need?

It needs to be screwed in. Use a pair of needle nose pliers, or you may find a universal tool at the parts store. Just apply slight pressure and turn it clockwise.

Takes some elbow grease. I use a spanner wrench for my angle grinder, it gives some extra leverage and makes it easier.