Oil is inadequate for this application; grease is required.

If the cheap pedals are pooched, then chuck them, and install another set. If the pedals are intact and spin reasonably well, then do this:

1. take a small nail and punch a hole in the plastic end-cap.
2. With a small grease ***, inject grease in the hole until the old nasty stuff comes out from the inside gap (near the crankarm)
3. Spin a few times and wipe up the surplus.

Good as new. Actually probably better than new, as these pedals typically were too tight and had too little grease.