stuck steering knuckle and brake caliper bolts

[Snibble]

I am on my way to replace the lower ball joint, but right when I was going to start by removing the brake caliper, the bolts are REALLY tight and appear "stuck". There doesn't seem to be any rust around the area.. just some brake dust that collected in the general area over the years. I was thinking of using wd-40... but is that a good idea considering there's the brake disk in the area?? Let me know what you recommend. THANKS IN ADVANCE!