wd40 to clean out the rust and a few pieces of pencil graphite(inserting the key will crush it) to relube everything as wd40 is a cleaner and will leave it dry, graphite is one of the best lubes for a lock, i've saved a number of friends krytonites that had been declared garbage with this method.

clif, what kind and size bolt cutters were you using?

I bought this same lock only with a cable. My kid needed a lock for her bike. I don't know who makes it but I noticed the key is the exact same as a cheap MasterLock U-lock I saw at Target. The HF lock itself looks similar to an OnGuard lock